diff --git a/csharp/src/ProtocolBuffers.Test/CodedInputStreamTest.cs b/csharp/src/ProtocolBuffers.Test/CodedInputStreamTest.cs
index 576500497..aa2da330e 100644
--- a/csharp/src/ProtocolBuffers.Test/CodedInputStreamTest.cs
+++ b/csharp/src/ProtocolBuffers.Test/CodedInputStreamTest.cs
@@ -466,18 +466,18 @@ namespace Google.Protobuf
             }
         }
 
-        enum TestNegEnum : long { None = 0, Value = -2 }
+        enum TestNegEnum { None = 0, Value = -2 }
 
         [Test]
         public void TestNegativeEnum()
         {
             byte[] bytes = new byte[10] { 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x01 };
             CodedInputStream input = CodedInputStream.CreateInstance(bytes);
-            TestNegEnum val = TestNegEnum.None;
+            int val = 0;
 
             Assert.IsTrue(input.ReadEnum(ref val));
             Assert.IsTrue(input.IsAtEnd);
-            Assert.AreEqual(TestNegEnum.Value, val);
+            Assert.AreEqual((int) TestNegEnum.Value, val);
         }
 
         [Test]
diff --git a/csharp/src/ProtocolBuffers.Test/CodedOutputStreamTest.cs b/csharp/src/ProtocolBuffers.Test/CodedOutputStreamTest.cs
index df80b3af5..fcbb7f8dc 100644
--- a/csharp/src/ProtocolBuffers.Test/CodedOutputStreamTest.cs
+++ b/csharp/src/ProtocolBuffers.Test/CodedOutputStreamTest.cs
@@ -296,27 +296,27 @@ namespace Google.Protobuf
         public void TestNegativeEnumNoTag()
         {
             Assert.AreEqual(10, CodedOutputStream.ComputeInt32SizeNoTag(-2));
-            Assert.AreEqual(10, CodedOutputStream.ComputeEnumSizeNoTag(TestNegEnum.Value));
+            Assert.AreEqual(10, CodedOutputStream.ComputeEnumSizeNoTag((int) TestNegEnum.Value));
 
             byte[] bytes = new byte[10];
             CodedOutputStream output = CodedOutputStream.CreateInstance(bytes);
-            output.WriteEnumNoTag(TestNegEnum.Value);
+            output.WriteEnumNoTag((int) TestNegEnum.Value);
 
             Assert.AreEqual(0, output.SpaceLeft);
             Assert.AreEqual("FE-FF-FF-FF-FF-FF-FF-FF-FF-01", BitConverter.ToString(bytes));
         }
 
-        enum TestNegEnum : long { None = 0, Value = -2 }
+        enum TestNegEnum { None = 0, Value = -2 }
 
         [Test]
         public void TestNegativeEnumWithTag()
         {
             Assert.AreEqual(11, CodedOutputStream.ComputeInt32Size(8, -2));
-            Assert.AreEqual(11, CodedOutputStream.ComputeEnumSize(8, TestNegEnum.Value));
+            Assert.AreEqual(11, CodedOutputStream.ComputeEnumSize(8, (int) TestNegEnum.Value));
 
             byte[] bytes = new byte[11];
             CodedOutputStream output = CodedOutputStream.CreateInstance(bytes);
-            output.WriteEnum(8, "", TestNegEnum.Value);
+            output.WriteEnum(8, "", (int) TestNegEnum.Value);
 
             Assert.AreEqual(0, output.SpaceLeft);
             //fyi, 0x40 == 0x08 << 3 + 0, field num + wire format shift
diff --git a/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestImportProto3.cs b/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestImportProto3.cs
index 1eb87f05c..4b62794a1 100644
--- a/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestImportProto3.cs
+++ b/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestImportProto3.cs
@@ -49,7 +49,7 @@ namespace Google.Protobuf.TestProtos {
 
   }
   #region Enums
-  public enum ImportEnum : long {
+  public enum ImportEnum {
     IMPORT_ENUM_UNSPECIFIED = 0,
     IMPORT_FOO = 7,
     IMPORT_BAR = 8,
diff --git a/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestIssues.cs b/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestIssues.cs
index fc696cf02..14ca78a41 100644
--- a/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestIssues.cs
+++ b/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestIssues.cs
@@ -75,13 +75,13 @@ namespace UnitTest.Issues.TestProtos {
 
   }
   #region Enums
-  public enum NegativeEnum : long {
+  public enum NegativeEnum {
     NEGATIVE_ENUM_ZERO = 0,
     FiveBelow = -5,
     MinusOne = -1,
   }
 
-  public enum DeprecatedEnum : long {
+  public enum DeprecatedEnum {
     DEPRECATED_ZERO = 0,
     one = 1,
   }
@@ -156,7 +156,7 @@ namespace UnitTest.Issues.TestProtos {
     public void WriteTo(pb::ICodedOutputStream output) {
       string[] fieldNames = _fieldNames;
       if (Value != global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO) {
-        output.WriteEnum(1, fieldNames[1], Value);
+        output.WriteEnum(1, fieldNames[1], (int) Value);
       }
       output.WriteEnumArray(2, fieldNames[2], values_);
       output.WritePackedEnumArray(3, fieldNames[0], packedValues_);
@@ -165,13 +165,13 @@ namespace UnitTest.Issues.TestProtos {
     public int CalculateSize() {
       int size = 0;
       if (Value != global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO) {
-        size += pb::CodedOutputStream.ComputeEnumSize(1, Value);
+        size += pb::CodedOutputStream.ComputeEnumSize(1, (int) Value);
       }
       {
         int dataSize = 0;
         if (values_.Count > 0) {
           foreach (global::UnitTest.Issues.TestProtos.NegativeEnum element in values_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 1 * values_.Count;
@@ -181,7 +181,7 @@ namespace UnitTest.Issues.TestProtos {
         int dataSize = 0;
         if (packedValues_.Count > 0) {
           foreach (global::UnitTest.Issues.TestProtos.NegativeEnum element in packedValues_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 1;
@@ -220,8 +220,9 @@ namespace UnitTest.Issues.TestProtos {
             }
             break;
           case 8: {
-            input.ReadEnum(ref value_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            value_ = (global::UnitTest.Issues.TestProtos.NegativeEnum) tmp;break;
           }
           case 18:
           case 16: {
@@ -422,7 +423,7 @@ namespace UnitTest.Issues.TestProtos {
       }
       output.WriteMessageArray(4, fieldNames[2], messageArray_);
       if (EnumValue != global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO) {
-        output.WriteEnum(5, fieldNames[1], EnumValue);
+        output.WriteEnum(5, fieldNames[1], (int) EnumValue);
       }
       output.WritePackedEnumArray(6, fieldNames[0], enumArray_);
     }
@@ -449,13 +450,13 @@ namespace UnitTest.Issues.TestProtos {
         size += pb::CodedOutputStream.ComputeMessageSize(4, element);
       }
       if (EnumValue != global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO) {
-        size += pb::CodedOutputStream.ComputeEnumSize(5, EnumValue);
+        size += pb::CodedOutputStream.ComputeEnumSize(5, (int) EnumValue);
       }
       {
         int dataSize = 0;
         if (enumArray_.Count > 0) {
           foreach (global::UnitTest.Issues.TestProtos.DeprecatedEnum element in enumArray_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 1;
@@ -524,8 +525,9 @@ namespace UnitTest.Issues.TestProtos {
             break;
           }
           case 40: {
-            input.ReadEnum(ref enumValue_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            enumValue_ = (global::UnitTest.Issues.TestProtos.DeprecatedEnum) tmp;break;
           }
           case 50:
           case 48: {
diff --git a/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestProto3.cs b/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestProto3.cs
index e231bb953..3e5bb8b69 100644
--- a/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestProto3.cs
+++ b/csharp/src/ProtocolBuffers.Test/TestProtos/UnittestProto3.cs
@@ -372,14 +372,14 @@ namespace Google.Protobuf.TestProtos {
 
   }
   #region Enums
-  public enum ForeignEnum : long {
+  public enum ForeignEnum {
     FOREIGN_UNSPECIFIED = 0,
     FOREIGN_FOO = 4,
     FOREIGN_BAR = 5,
     FOREIGN_BAZ = 6,
   }
 
-  public enum TestEnumWithDupValue : long {
+  public enum TestEnumWithDupValue {
     TEST_ENUM_WITH_DUP_VALUE_UNSPECIFIED = 0,
     FOO1 = 1,
     BAR1 = 2,
@@ -388,7 +388,7 @@ namespace Google.Protobuf.TestProtos {
     BAR2 = 2,
   }
 
-  public enum TestSparseEnum : long {
+  public enum TestSparseEnum {
     TEST_SPARSE_ENUM_UNSPECIFIED = 0,
     SPARSE_A = 123,
     SPARSE_B = 62374,
@@ -945,13 +945,13 @@ namespace Google.Protobuf.TestProtos {
         output.WriteMessage(20, fieldNames[35], SingleImportMessage);
       }
       if (SingleNestedEnum != global::Google.Protobuf.TestProtos.TestAllTypes.Types.NestedEnum.NESTED_ENUM_UNSPECIFIED) {
-        output.WriteEnum(21, fieldNames[38], SingleNestedEnum);
+        output.WriteEnum(21, fieldNames[38], (int) SingleNestedEnum);
       }
       if (SingleForeignEnum != global::Google.Protobuf.TestProtos.ForeignEnum.FOREIGN_UNSPECIFIED) {
-        output.WriteEnum(22, fieldNames[32], SingleForeignEnum);
+        output.WriteEnum(22, fieldNames[32], (int) SingleForeignEnum);
       }
       if (SingleImportEnum != global::Google.Protobuf.TestProtos.ImportEnum.IMPORT_ENUM_UNSPECIFIED) {
-        output.WriteEnum(23, fieldNames[34], SingleImportEnum);
+        output.WriteEnum(23, fieldNames[34], (int) SingleImportEnum);
       }
       if (singlePublicImportMessage_ != null) {
         output.WriteMessage(26, fieldNames[40], SinglePublicImportMessage);
@@ -1049,13 +1049,13 @@ namespace Google.Protobuf.TestProtos {
         size += pb::CodedOutputStream.ComputeMessageSize(20, SingleImportMessage);
       }
       if (SingleNestedEnum != global::Google.Protobuf.TestProtos.TestAllTypes.Types.NestedEnum.NESTED_ENUM_UNSPECIFIED) {
-        size += pb::CodedOutputStream.ComputeEnumSize(21, SingleNestedEnum);
+        size += pb::CodedOutputStream.ComputeEnumSize(21, (int) SingleNestedEnum);
       }
       if (SingleForeignEnum != global::Google.Protobuf.TestProtos.ForeignEnum.FOREIGN_UNSPECIFIED) {
-        size += pb::CodedOutputStream.ComputeEnumSize(22, SingleForeignEnum);
+        size += pb::CodedOutputStream.ComputeEnumSize(22, (int) SingleForeignEnum);
       }
       if (SingleImportEnum != global::Google.Protobuf.TestProtos.ImportEnum.IMPORT_ENUM_UNSPECIFIED) {
-        size += pb::CodedOutputStream.ComputeEnumSize(23, SingleImportEnum);
+        size += pb::CodedOutputStream.ComputeEnumSize(23, (int) SingleImportEnum);
       }
       if (singlePublicImportMessage_ != null) {
         size += pb::CodedOutputStream.ComputeMessageSize(26, SinglePublicImportMessage);
@@ -1205,7 +1205,7 @@ namespace Google.Protobuf.TestProtos {
         int dataSize = 0;
         if (repeatedNestedEnum_.Count > 0) {
           foreach (global::Google.Protobuf.TestProtos.TestAllTypes.Types.NestedEnum element in repeatedNestedEnum_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 2;
@@ -1216,7 +1216,7 @@ namespace Google.Protobuf.TestProtos {
         int dataSize = 0;
         if (repeatedForeignEnum_.Count > 0) {
           foreach (global::Google.Protobuf.TestProtos.ForeignEnum element in repeatedForeignEnum_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 2;
@@ -1227,7 +1227,7 @@ namespace Google.Protobuf.TestProtos {
         int dataSize = 0;
         if (repeatedImportEnum_.Count > 0) {
           foreach (global::Google.Protobuf.TestProtos.ImportEnum element in repeatedImportEnum_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 2;
@@ -1472,16 +1472,19 @@ namespace Google.Protobuf.TestProtos {
             break;
           }
           case 168: {
-            input.ReadEnum(ref singleNestedEnum_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            singleNestedEnum_ = (global::Google.Protobuf.TestProtos.TestAllTypes.Types.NestedEnum) tmp;break;
           }
           case 176: {
-            input.ReadEnum(ref singleForeignEnum_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            singleForeignEnum_ = (global::Google.Protobuf.TestProtos.ForeignEnum) tmp;break;
           }
           case 184: {
-            input.ReadEnum(ref singleImportEnum_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            singleImportEnum_ = (global::Google.Protobuf.TestProtos.ImportEnum) tmp;break;
           }
           case 210: {
             if (singlePublicImportMessage_ == null) {
@@ -1634,7 +1637,7 @@ namespace Google.Protobuf.TestProtos {
     #region Nested types
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
-      public enum NestedEnum : long {
+      public enum NestedEnum {
         NESTED_ENUM_UNSPECIFIED = 0,
         FOO = 1,
         BAR = 2,
@@ -2865,7 +2868,7 @@ namespace Google.Protobuf.TestProtos {
         output.WriteString(2, fieldNames[7], StringField);
       }
       if (EnumField != global::Google.Protobuf.TestProtos.ForeignEnum.FOREIGN_UNSPECIFIED) {
-        output.WriteEnum(3, fieldNames[0], EnumField);
+        output.WriteEnum(3, fieldNames[0], (int) EnumField);
       }
       if (messageField_ != null) {
         output.WriteMessage(4, fieldNames[1], MessageField);
@@ -2885,7 +2888,7 @@ namespace Google.Protobuf.TestProtos {
         size += pb::CodedOutputStream.ComputeStringSize(2, StringField);
       }
       if (EnumField != global::Google.Protobuf.TestProtos.ForeignEnum.FOREIGN_UNSPECIFIED) {
-        size += pb::CodedOutputStream.ComputeEnumSize(3, EnumField);
+        size += pb::CodedOutputStream.ComputeEnumSize(3, (int) EnumField);
       }
       if (messageField_ != null) {
         size += pb::CodedOutputStream.ComputeMessageSize(4, MessageField);
@@ -2912,7 +2915,7 @@ namespace Google.Protobuf.TestProtos {
         int dataSize = 0;
         if (repeatedEnumField_.Count > 0) {
           foreach (global::Google.Protobuf.TestProtos.ForeignEnum element in repeatedEnumField_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 1;
@@ -2976,8 +2979,9 @@ namespace Google.Protobuf.TestProtos {
             break;
           }
           case 24: {
-            input.ReadEnum(ref enumField_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            enumField_ = (global::Google.Protobuf.TestProtos.ForeignEnum) tmp;break;
           }
           case 34: {
             if (messageField_ == null) {
@@ -3361,14 +3365,14 @@ namespace Google.Protobuf.TestProtos {
     public void WriteTo(pb::ICodedOutputStream output) {
       string[] fieldNames = _fieldNames;
       if (SparseEnum != global::Google.Protobuf.TestProtos.TestSparseEnum.TEST_SPARSE_ENUM_UNSPECIFIED) {
-        output.WriteEnum(1, fieldNames[0], SparseEnum);
+        output.WriteEnum(1, fieldNames[0], (int) SparseEnum);
       }
     }
 
     public int CalculateSize() {
       int size = 0;
       if (SparseEnum != global::Google.Protobuf.TestProtos.TestSparseEnum.TEST_SPARSE_ENUM_UNSPECIFIED) {
-        size += pb::CodedOutputStream.ComputeEnumSize(1, SparseEnum);
+        size += pb::CodedOutputStream.ComputeEnumSize(1, (int) SparseEnum);
       }
       return size;
     }
@@ -3400,8 +3404,9 @@ namespace Google.Protobuf.TestProtos {
             }
             break;
           case 8: {
-            input.ReadEnum(ref sparseEnum_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            sparseEnum_ = (global::Google.Protobuf.TestProtos.TestSparseEnum) tmp;break;
           }
         }
       }
@@ -4769,7 +4774,7 @@ namespace Google.Protobuf.TestProtos {
         int dataSize = 0;
         if (packedEnum_.Count > 0) {
           foreach (global::Google.Protobuf.TestProtos.ForeignEnum element in packedEnum_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 2;
@@ -5156,7 +5161,7 @@ namespace Google.Protobuf.TestProtos {
         int dataSize = 0;
         if (unpackedEnum_.Count > 0) {
           foreach (global::Google.Protobuf.TestProtos.ForeignEnum element in unpackedEnum_) {
-            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);
+            dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);
           }
           size += dataSize;
           size += 2 * unpackedEnum_.Count;
diff --git a/csharp/src/ProtocolBuffers/CodedInputStream.cs b/csharp/src/ProtocolBuffers/CodedInputStream.cs
index 685d77026..d5cab6fd7 100644
--- a/csharp/src/ProtocolBuffers/CodedInputStream.cs
+++ b/csharp/src/ProtocolBuffers/CodedInputStream.cs
@@ -434,11 +434,10 @@ namespace Google.Protobuf
         /// then the ref value is set and it returns true.  Otherwise the unknown output
         /// value is set and this method returns false.
         /// </summary>   
-        public bool ReadEnum<T>(ref T value)
-            where T : struct, IComparable, IFormattable
+        public bool ReadEnum(ref int value)
         {
-            int number = (int) ReadRawVarint32();
-            value = EnumHelper<T>.FromInt32(number);
+            // Currently just a pass-through, but it's nice to separate it logically from WriteInt32.
+            value = (int) ReadRawVarint32();
             return true;
         }
 
@@ -796,7 +795,7 @@ namespace Google.Protobuf
         public void ReadEnumArray<T>(uint fieldTag, string fieldName, ICollection<T> list)
             where T : struct, IComparable, IFormattable
         {
-            T value = default(T);
+            int value = 0;
             WireFormat.WireType wformat = WireFormat.GetTagWireType(fieldTag);
 
             // 2.3 allows packed form even if the field is not declared packed.
@@ -806,8 +805,9 @@ namespace Google.Protobuf
                 int limit = PushLimit(length);
                 while (!ReachedLimit)
                 {
-                    ReadEnum<T>(ref value);
-                    list.Add(value);
+                    ReadEnum(ref value);
+                    // TODO(jonskeet): Avoid this horrible boxing!
+                    list.Add((T)(object)value);
                 }
                 PopLimit(limit);
             }
@@ -816,7 +816,8 @@ namespace Google.Protobuf
                 do
                 {
                     ReadEnum(ref value);
-                    list.Add(value);
+                    // TODO(jonskeet): Avoid this horrible boxing!
+                    list.Add((T)(object) value);
                 } while (ContinueArray(fieldTag));
             }
         }
diff --git a/csharp/src/ProtocolBuffers/CodedOutputStream.ComputeSize.cs b/csharp/src/ProtocolBuffers/CodedOutputStream.ComputeSize.cs
index 58475ff7b..96be9db56 100644
--- a/csharp/src/ProtocolBuffers/CodedOutputStream.ComputeSize.cs
+++ b/csharp/src/ProtocolBuffers/CodedOutputStream.ComputeSize.cs
@@ -196,7 +196,7 @@ namespace Google.Protobuf
         /// enum field, including the tag. The caller is responsible for
         /// converting the enum value to its numeric value.
         /// </summary>
-        public static int ComputeEnumSize<T>(int fieldNumber, T value) where T : struct, IComparable, IFormattable
+        public static int ComputeEnumSize(int fieldNumber, int value)
         {
             return ComputeTagSize(fieldNumber) + ComputeEnumSizeNoTag(value);
         }
@@ -371,10 +371,10 @@ namespace Google.Protobuf
         /// enum field, including the tag. The caller is responsible for
         /// converting the enum value to its numeric value.
         /// </summary>
-        public static int ComputeEnumSizeNoTag<T>(T value) where T : struct, IComparable, IFormattable
+        public static int ComputeEnumSizeNoTag(int value)
         {
-            int serializedValue = EnumHelper<T>.ToInt32(value);
-            return ComputeInt32SizeNoTag(serializedValue);
+            // Currently just a pass-through, but it's nice to separate it logically.
+            return ComputeInt32SizeNoTag(value);
         }
 
         /// <summary>
@@ -555,7 +555,7 @@ namespace Google.Protobuf
                 case FieldType.SInt64:
                     return ComputeSInt64Size(fieldNumber, (long) value);
                 case FieldType.Enum:
-                    return ComputeEnumSize(fieldNumber, Convert.ToInt64(value));
+                    return ComputeEnumSize(fieldNumber, (int) value);
                 default:
                     throw new ArgumentOutOfRangeException("Invalid field type " + fieldType);
             }
@@ -605,7 +605,7 @@ namespace Google.Protobuf
                 case FieldType.SInt64:
                     return ComputeSInt64SizeNoTag((long) value);
                 case FieldType.Enum:
-                    return ComputeEnumSizeNoTag(Convert.ToInt64(value));
+                    return ComputeEnumSizeNoTag((int) value);
                 default:
                     throw new ArgumentOutOfRangeException("Invalid field type " + fieldType);
             }
diff --git a/csharp/src/ProtocolBuffers/CodedOutputStream.cs b/csharp/src/ProtocolBuffers/CodedOutputStream.cs
index f55f8ca2f..e3f0c7007 100644
--- a/csharp/src/ProtocolBuffers/CodedOutputStream.cs
+++ b/csharp/src/ProtocolBuffers/CodedOutputStream.cs
@@ -37,6 +37,7 @@
 using System;
 using System.Collections;
 using System.IO;
+using System.Linq;
 using System.Text;
 using Google.Protobuf.Collections;
 using Google.Protobuf.Descriptors;
@@ -350,10 +351,11 @@ namespace Google.Protobuf
             WriteRawVarint32(value);
         }
 
-        public void WriteEnum<T>(int fieldNumber, string fieldName, T value) where T : struct, IComparable, IFormattable
+        public void WriteEnum(int fieldNumber, string fieldName, int value)
         {
+            // Currently just a pass-through, but it's nice to separate it logically from WriteInt32.
             WriteTag(fieldNumber, WireFormat.WireType.Varint);
-            WriteInt32NoTag(EnumHelper<T>.ToInt32(value));
+            WriteInt32NoTag(value);
         }
 
         public void WriteSFixed32(int fieldNumber, string fieldName, int value)
@@ -595,9 +597,9 @@ namespace Google.Protobuf
             WriteRawVarint32(value);
         }
 
-        public void WriteEnumNoTag<T>(T value) where T : struct, IComparable, IFormattable
+        public void WriteEnumNoTag(int value)
         {
-            WriteInt32NoTag(EnumHelper<T>.ToInt32(value));
+            WriteInt32NoTag(value);
         }
 
         public void WriteSFixed32NoTag(int value)
@@ -774,7 +776,12 @@ namespace Google.Protobuf
         public void WriteEnumArray<T>(int fieldNumber, string fieldName, RepeatedField<T> list)
             where T : struct, IComparable, IFormattable
         {
-            foreach (T value in list)
+            if (list.Count == 0)
+            {
+                return;
+            }
+            // TODO(jonskeet): Avoid the Cast call here. Work out a better mass "T to int" conversion.
+            foreach (int value in list.Cast<int>())
             {
                 WriteEnum(fieldNumber, fieldName, value);
             }
@@ -1005,10 +1012,13 @@ namespace Google.Protobuf
             {
                 return;
             }
-            uint size = list.CalculateSize(ComputeEnumSizeNoTag);
+            // Obviously, we'll want to get rid of this hack...
+            var temporaryHack = new RepeatedField<int>();
+            temporaryHack.Add(list.Cast<int>());
+            uint size = temporaryHack.CalculateSize(ComputeEnumSizeNoTag);
             WriteTag(fieldNumber, WireFormat.WireType.LengthDelimited);
             WriteRawVarint32(size);
-            foreach (T value in list)
+            foreach (int value in temporaryHack)
             {
                 WriteEnumNoTag(value);
             }
diff --git a/csharp/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs b/csharp/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs
index b18b63bf7..eb96dfcf5 100644
--- a/csharp/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs
+++ b/csharp/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs
@@ -1360,10 +1360,10 @@ namespace Google.Protobuf.DescriptorProtos {
         output.WriteInt32(3, fieldNames[4], Number);
       }
       if (Label != global::Google.Protobuf.DescriptorProtos.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL) {
-        output.WriteEnum(4, fieldNames[2], Label);
+        output.WriteEnum(4, fieldNames[2], (int) Label);
       }
       if (Type != global::Google.Protobuf.DescriptorProtos.FieldDescriptorProto.Types.Type.TYPE_DOUBLE) {
-        output.WriteEnum(5, fieldNames[7], Type);
+        output.WriteEnum(5, fieldNames[7], (int) Type);
       }
       if (TypeName != "") {
         output.WriteString(6, fieldNames[8], TypeName);
@@ -1388,10 +1388,10 @@ namespace Google.Protobuf.DescriptorProtos {
         size += pb::CodedOutputStream.ComputeInt32Size(3, Number);
       }
       if (Label != global::Google.Protobuf.DescriptorProtos.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL) {
-        size += pb::CodedOutputStream.ComputeEnumSize(4, Label);
+        size += pb::CodedOutputStream.ComputeEnumSize(4, (int) Label);
       }
       if (Type != global::Google.Protobuf.DescriptorProtos.FieldDescriptorProto.Types.Type.TYPE_DOUBLE) {
-        size += pb::CodedOutputStream.ComputeEnumSize(5, Type);
+        size += pb::CodedOutputStream.ComputeEnumSize(5, (int) Type);
       }
       if (TypeName != "") {
         size += pb::CodedOutputStream.ComputeStringSize(6, TypeName);
@@ -1477,12 +1477,14 @@ namespace Google.Protobuf.DescriptorProtos {
             break;
           }
           case 32: {
-            input.ReadEnum(ref label_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            label_ = (global::Google.Protobuf.DescriptorProtos.FieldDescriptorProto.Types.Label) tmp;break;
           }
           case 40: {
-            input.ReadEnum(ref type_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            type_ = (global::Google.Protobuf.DescriptorProtos.FieldDescriptorProto.Types.Type) tmp;break;
           }
           case 50: {
             input.ReadString(ref typeName_);
@@ -1510,7 +1512,7 @@ namespace Google.Protobuf.DescriptorProtos {
     #region Nested types
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
-      public enum Type : long {
+      public enum Type {
         TYPE_DOUBLE = 1,
         TYPE_FLOAT = 2,
         TYPE_INT64 = 3,
@@ -1531,7 +1533,7 @@ namespace Google.Protobuf.DescriptorProtos {
         TYPE_SINT64 = 18,
       }
 
-      public enum Label : long {
+      public enum Label {
         LABEL_OPTIONAL = 1,
         LABEL_REQUIRED = 2,
         LABEL_REPEATED = 3,
@@ -2489,7 +2491,7 @@ namespace Google.Protobuf.DescriptorProtos {
         output.WriteString(8, fieldNames[8], JavaOuterClassname);
       }
       if (OptimizeFor != global::Google.Protobuf.DescriptorProtos.FileOptions.Types.OptimizeMode.SPEED) {
-        output.WriteEnum(9, fieldNames[12], OptimizeFor);
+        output.WriteEnum(9, fieldNames[12], (int) OptimizeFor);
       }
       if (JavaMultipleFiles != false) {
         output.WriteBool(10, fieldNames[7], JavaMultipleFiles);
@@ -2545,7 +2547,7 @@ namespace Google.Protobuf.DescriptorProtos {
         size += pb::CodedOutputStream.ComputeBoolSize(27, JavaStringCheckUtf8);
       }
       if (OptimizeFor != global::Google.Protobuf.DescriptorProtos.FileOptions.Types.OptimizeMode.SPEED) {
-        size += pb::CodedOutputStream.ComputeEnumSize(9, OptimizeFor);
+        size += pb::CodedOutputStream.ComputeEnumSize(9, (int) OptimizeFor);
       }
       if (GoPackage != "") {
         size += pb::CodedOutputStream.ComputeStringSize(11, GoPackage);
@@ -2652,8 +2654,9 @@ namespace Google.Protobuf.DescriptorProtos {
             break;
           }
           case 72: {
-            input.ReadEnum(ref optimizeFor_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            optimizeFor_ = (global::Google.Protobuf.DescriptorProtos.FileOptions.Types.OptimizeMode) tmp;break;
           }
           case 80: {
             input.ReadBool(ref javaMultipleFiles_);
@@ -2710,7 +2713,7 @@ namespace Google.Protobuf.DescriptorProtos {
     #region Nested types
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
-      public enum OptimizeMode : long {
+      public enum OptimizeMode {
         SPEED = 1,
         CODE_SIZE = 2,
         LITE_RUNTIME = 3,
@@ -3015,7 +3018,7 @@ namespace Google.Protobuf.DescriptorProtos {
     public void WriteTo(pb::ICodedOutputStream output) {
       string[] fieldNames = _fieldNames;
       if (Ctype != global::Google.Protobuf.DescriptorProtos.FieldOptions.Types.CType.STRING) {
-        output.WriteEnum(1, fieldNames[0], Ctype);
+        output.WriteEnum(1, fieldNames[0], (int) Ctype);
       }
       if (Packed != false) {
         output.WriteBool(2, fieldNames[4], Packed);
@@ -3027,7 +3030,7 @@ namespace Google.Protobuf.DescriptorProtos {
         output.WriteBool(5, fieldNames[3], Lazy);
       }
       if (Jstype != global::Google.Protobuf.DescriptorProtos.FieldOptions.Types.JSType.JS_NORMAL) {
-        output.WriteEnum(6, fieldNames[2], Jstype);
+        output.WriteEnum(6, fieldNames[2], (int) Jstype);
       }
       if (Weak != false) {
         output.WriteBool(10, fieldNames[6], Weak);
@@ -3038,13 +3041,13 @@ namespace Google.Protobuf.DescriptorProtos {
     public int CalculateSize() {
       int size = 0;
       if (Ctype != global::Google.Protobuf.DescriptorProtos.FieldOptions.Types.CType.STRING) {
-        size += pb::CodedOutputStream.ComputeEnumSize(1, Ctype);
+        size += pb::CodedOutputStream.ComputeEnumSize(1, (int) Ctype);
       }
       if (Packed != false) {
         size += pb::CodedOutputStream.ComputeBoolSize(2, Packed);
       }
       if (Jstype != global::Google.Protobuf.DescriptorProtos.FieldOptions.Types.JSType.JS_NORMAL) {
-        size += pb::CodedOutputStream.ComputeEnumSize(6, Jstype);
+        size += pb::CodedOutputStream.ComputeEnumSize(6, (int) Jstype);
       }
       if (Lazy != false) {
         size += pb::CodedOutputStream.ComputeBoolSize(5, Lazy);
@@ -3104,8 +3107,9 @@ namespace Google.Protobuf.DescriptorProtos {
             }
             break;
           case 8: {
-            input.ReadEnum(ref ctype_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            ctype_ = (global::Google.Protobuf.DescriptorProtos.FieldOptions.Types.CType) tmp;break;
           }
           case 16: {
             input.ReadBool(ref packed_);
@@ -3120,8 +3124,9 @@ namespace Google.Protobuf.DescriptorProtos {
             break;
           }
           case 48: {
-            input.ReadEnum(ref jstype_);
-            break;
+            int tmp = 0;
+            input.ReadEnum(ref tmp);
+            jstype_ = (global::Google.Protobuf.DescriptorProtos.FieldOptions.Types.JSType) tmp;break;
           }
           case 80: {
             input.ReadBool(ref weak_);
@@ -3138,13 +3143,13 @@ namespace Google.Protobuf.DescriptorProtos {
     #region Nested types
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
-      public enum CType : long {
+      public enum CType {
         STRING = 0,
         CORD = 1,
         STRING_PIECE = 2,
       }
 
-      public enum JSType : long {
+      public enum JSType {
         JS_NORMAL = 0,
         JS_STRING = 1,
         JS_NUMBER = 2,
diff --git a/csharp/src/ProtocolBuffers/EnumHelper.cs b/csharp/src/ProtocolBuffers/EnumHelper.cs
deleted file mode 100644
index 1cf189858..000000000
--- a/csharp/src/ProtocolBuffers/EnumHelper.cs
+++ /dev/null
@@ -1,93 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace Google.Protobuf
-{
-    public class EnumHelper<T> where T : struct, IComparable, IFormattable
-    {
-        // TODO(jonskeet): For snmall enums, use something lighter-weight than a dictionary?
-        private static readonly Dictionary<int, T> _byNumber;
-        private static readonly Dictionary<string, T> _byName;
-        private static readonly Func<T, long> toRawValue;
-        private static readonly Func<long, T> fromRawValue;
-
-        private const long UnknownValueBase = 0x100000000L;
-
-        static EnumHelper()
-        {
-            if (!typeof(T).IsEnum)
-            {
-                throw new InvalidOperationException(string.Format("{0} is not an enum type", typeof(T).FullName));
-            }
-            if (Enum.GetUnderlyingType(typeof(T)) != typeof(long))
-            {
-                throw new InvalidOperationException(string.Format("{0} does not have long as an underlying type", typeof(T).FullName));
-            }
-            // It will actually be a T[], but the CLR will let us convert.
-            long[] array = (long[])Enum.GetValues(typeof(T));
-            _byNumber = new Dictionary<int, T>(array.Length);
-            foreach (long i in array)
-            {
-                _byNumber[(int) i] = (T)(object)i;
-            }
-            string[] names = (string[])Enum.GetNames(typeof(T));
-            _byName = new Dictionary<string, T>();
-            foreach (var name in names)
-            {
-                _byName[name] = (T) Enum.Parse(typeof(T), name, false);
-            }
-
-            ParameterExpression param1 = Expression.Parameter(typeof(T), "x");
-            ParameterExpression param2 = Expression.Parameter(typeof(long), "x");
-            Expression convertedParam1 = Expression.Convert(param1, typeof(long));
-            Expression convertedParam2 = Expression.Convert(param2, typeof(T));
-            toRawValue = Expression.Lambda<Func<T, long>>(convertedParam1, param1).Compile();
-            fromRawValue = Expression.Lambda<Func<long, T>>(convertedParam2, param2).Compile();
-        }
-
-        /// <summary>
-        /// Converts the given 32-bit integer into a value of the enum type.
-        /// If the integer is a known, named value, that is returned; otherwise,
-        /// a value which is outside the range of 32-bit integers but which preserves
-        /// the original integer is returned.
-        /// </summary>
-        public static T FromInt32(int value)
-        {
-            T validValue;
-            return _byNumber.TryGetValue(value, out validValue) ? validValue : FromRawValue((long) value | UnknownValueBase);
-        }
-
-        /// <summary>
-        /// Converts a value of the enum type to a 32-bit integer. This reverses
-        /// <see cref="Int32"/>.
-        /// </summary>
-        public static int ToInt32(T value)
-        {
-            return (int)GetRawValue(value);
-        }
-
-        public static bool IsKnownValue(T value)
-        {
-            long raw = GetRawValue(value);
-            if (raw >= int.MinValue && raw <= int.MaxValue)
-            {
-                return _byNumber.ContainsKey((int)raw);
-            }
-            return false;
-        }
-
-        private static long GetRawValue(T value)
-        {
-            return toRawValue(value);
-        }
-
-        private static T FromRawValue(long value)
-        {
-            return fromRawValue(value);
-        }
-
-    }
-}
diff --git a/csharp/src/ProtocolBuffers/ICodedInputStream.cs b/csharp/src/ProtocolBuffers/ICodedInputStream.cs
index 748589a00..d962e62bf 100644
--- a/csharp/src/ProtocolBuffers/ICodedInputStream.cs
+++ b/csharp/src/ProtocolBuffers/ICodedInputStream.cs
@@ -146,14 +146,11 @@ namespace Google.Protobuf
         bool ReadUInt32(ref uint value);
 
         /// <summary>
-        /// Reads an enum field value from the stream. If the enum is valid for type T,
-        /// then the ref value is set and it returns true. Otherwise, if a value is present
-        /// but invalid for the proto enum, it is still set in the field as a "preserved
-        /// but invalid" value, and the method returns true. If no value can be read, the
-        /// method does not affect the parameter and returns false.
+        /// Reads an enum field value from the stream. This performs no checking
+        /// as to whether the enum value is known to the enum type as it was present
+        /// when the code was generated.
         /// </summary>   
-        bool ReadEnum<T>(ref T value)
-            where T : struct, IComparable, IFormattable;
+        bool ReadEnum(ref int value);
 
         /// <summary>
         /// Reads an sfixed32 field value from the stream.
diff --git a/csharp/src/ProtocolBuffers/ICodedOutputStream.cs b/csharp/src/ProtocolBuffers/ICodedOutputStream.cs
index e51c10a49..921400aca 100644
--- a/csharp/src/ProtocolBuffers/ICodedOutputStream.cs
+++ b/csharp/src/ProtocolBuffers/ICodedOutputStream.cs
@@ -148,7 +148,7 @@ namespace Google.Protobuf
         /// <summary>
         /// Writes an enum field value, including tag, to the stream.
         /// </summary>
-        void WriteEnum<T>(int fieldNumber, string fieldName, T value) where T : struct, IComparable, IFormattable;
+        void WriteEnum(int fieldNumber, string fieldName, int value);
 
         /// <summary>
         /// Writes a fixed 32-bit field value, including tag, to the stream.
diff --git a/csharp/src/ProtocolBuffers/ProtocolBuffers.csproj b/csharp/src/ProtocolBuffers/ProtocolBuffers.csproj
index d15f13069..efd387a27 100644
--- a/csharp/src/ProtocolBuffers/ProtocolBuffers.csproj
+++ b/csharp/src/ProtocolBuffers/ProtocolBuffers.csproj
@@ -84,7 +84,6 @@
     <Compile Include="Descriptors\MethodDescriptor.cs" />
     <Compile Include="Descriptors\PackageDescriptor.cs" />
     <Compile Include="Descriptors\ServiceDescriptor.cs" />
-    <Compile Include="EnumHelper.cs" />
     <Compile Include="Extensions.cs" />
     <Compile Include="FieldAccess\FieldAccessorBase.cs" />
     <Compile Include="FieldAccess\ReflectionUtil.cs" />
diff --git a/src/google/protobuf/compiler/csharp/csharp_enum.cc b/src/google/protobuf/compiler/csharp/csharp_enum.cc
index d511bba3b..0e8f98369 100644
--- a/src/google/protobuf/compiler/csharp/csharp_enum.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_enum.cc
@@ -58,7 +58,7 @@ EnumGenerator::~EnumGenerator() {
 
 void EnumGenerator::Generate(io::Printer* printer) {
   WriteGeneratedCodeAttributes(printer);
-  printer->Print("$access_level$ enum $name$ : long {\n",
+  printer->Print("$access_level$ enum $name$ {\n",
                  "access_level", class_access_level(),
                  "name", descriptor_->name());
   printer->Indent();
diff --git a/src/google/protobuf/compiler/csharp/csharp_enum_field.cc b/src/google/protobuf/compiler/csharp/csharp_enum_field.cc
index ee9d6a1d2..3494b2280 100644
--- a/src/google/protobuf/compiler/csharp/csharp_enum_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_enum_field.cc
@@ -54,14 +54,17 @@ EnumFieldGenerator::~EnumFieldGenerator() {
 }
 
 void EnumFieldGenerator::GenerateParsingCode(io::Printer* printer) {
+  // TODO(jonskeet): Get rid of the temporary variable when we sanitize CodedInputStream not to use ref.
   printer->Print(variables_,
-    "input.ReadEnum(ref $name$_);\n");
+    "int tmp = 0;\n"
+    "input.ReadEnum(ref tmp);\n"
+    "$name$_ = ($type_name$) tmp;");
 }
 
 void EnumFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(variables_,
     "if ($has_property_check$) {\n"
-    "  output.WriteEnum($number$, fieldNames[$field_ordinal$], $property_name$);\n"
+    "  output.WriteEnum($number$, fieldNames[$field_ordinal$], (int) $property_name$);\n"
     "}\n");
 }
 
@@ -69,7 +72,7 @@ void EnumFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  size += pb::CodedOutputStream.ComputeEnumSize($number$, $property_name$);\n"
+      "  size += pb::CodedOutputStream.ComputeEnumSize($number$, (int) $property_name$);\n"
     "}\n");
 }
 
@@ -85,7 +88,7 @@ void EnumOneofFieldGenerator::GenerateParsingCode(io::Printer* printer) {
   // TODO(jonskeet): What about if we read the default value?
   printer->Print(
     variables_,
-    "$type_name$ enumValue = $default_value$;\n"
+    "int enumValue = 0;\n"
     "if(input.ReadEnum(ref enumValue)) {\n"
     "  $oneof_name$_ = enumValue;\n"
     "  $oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
@@ -96,7 +99,7 @@ void EnumOneofFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  output.WriteEnum($number$, fieldNames[$field_ordinal$], (long) $property_name$, $property_name$);\n"
+    "  output.WriteEnum($number$, fieldNames[$field_ordinal$], (int) $property_name$);\n"
     "}\n");
 }
 
@@ -104,7 +107,7 @@ void EnumOneofFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  size += pb::CodedOutputStream.ComputeEnumSize($number$, (long) $property_name$);\n"
+    "  size += pb::CodedOutputStream.ComputeEnumSize($number$, (int) $property_name$);\n"
     "}\n");
 }
 
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
index ebbbf3bee..937d675a5 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
@@ -99,7 +99,7 @@ void RepeatedEnumFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer
   printer->Print(
     variables_,
     "foreach ($type_name$ element in $name$_) {\n"
-    "  dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag(element);\n"
+    "  dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);\n"
     "}\n"
     "size += dataSize;\n");
   int tagSize = internal::WireFormat::TagSize(descriptor_->number(), descriptor_->type());