diff --git a/src/main/java/net/md_5/specialsource/JarRemapper.java b/src/main/java/net/md_5/specialsource/JarRemapper.java
index 71e2196..8d0a331 100644
--- a/src/main/java/net/md_5/specialsource/JarRemapper.java
+++ b/src/main/java/net/md_5/specialsource/JarRemapper.java
@@ -57,20 +57,19 @@ public class JarRemapper extends Remapper {
 
     @Override
     public String map(String typeName) {
-        return mapTypeName(typeName, jarMapping.packages, jarMapping.classes);
+        return mapTypeName(typeName, jarMapping.packages, jarMapping.classes, typeName);
     }
 
-    public static String mapTypeName(String typeName, Map<String, String> packageMap, Map<String, String> classMap) {
+    public static String mapTypeName(String typeName, Map<String, String> packageMap, Map<String, String> classMap, String defaultIfUnmapped) {
         int index = typeName.indexOf('$');
         String key = (index == -1) ? typeName : typeName.substring(0, index);
         String mapped = mapClassName(key, packageMap, classMap);
 
-        return mapped != null ? mapped + (index == -1 ? "" : typeName.substring(index, typeName.length())) : typeName;
+        return mapped != null ? mapped + (index == -1 ? "" : typeName.substring(index, typeName.length())) : defaultIfUnmapped;
     }
 
     /**
      * Helper method to map a class name by package (prefix) or class (exact)
-     * map
      */
     private static String mapClassName(String className, Map<String, String> packageMap, Map<String, String> classMap) {
         if (packageMap != null) {
diff --git a/src/main/java/net/md_5/specialsource/MethodDescriptorTransformer.java b/src/main/java/net/md_5/specialsource/MethodDescriptorTransformer.java
index a35cd28..20bfbe8 100644
--- a/src/main/java/net/md_5/specialsource/MethodDescriptorTransformer.java
+++ b/src/main/java/net/md_5/specialsource/MethodDescriptorTransformer.java
@@ -57,7 +57,7 @@ public class MethodDescriptorTransformer {
                     String className = rest.substring(1, end);
                     i += className.length() + 1;
 
-                    String newClassName = JarRemapper.mapTypeName(className, packageMap, classMap);
+                    String newClassName = JarRemapper.mapTypeName(className, packageMap, classMap, className);
 
                     output.append("L").append(newClassName).append(";");
                     break;
diff --git a/src/main/java/net/md_5/specialsource/RemappedRuntimeInheritanceProvider.java b/src/main/java/net/md_5/specialsource/RemappedRuntimeInheritanceProvider.java
index eaa66fe..8db1db7 100644
--- a/src/main/java/net/md_5/specialsource/RemappedRuntimeInheritanceProvider.java
+++ b/src/main/java/net/md_5/specialsource/RemappedRuntimeInheritanceProvider.java
@@ -31,7 +31,14 @@ public class RemappedRuntimeInheritanceProvider extends RuntimeInheritanceProvid
     @Override
     public List<String> getParents(String before) {
         // Remap the input (example: cb -> obf)
-        String after = JarRemapper.mapTypeName(before, jarMapping.packages, jarMapping.classes);
+        // If the type is not mapped, return immediately
+        String after = JarRemapper.mapTypeName(before, jarMapping.packages, jarMapping.classes, null);
+        if (after == null) {
+            if (verbose) {
+                System.out.println("RemappedRuntimeInheritanceProvider doesn't know about "+before);
+            }
+            return null;
+        }
 
         if (verbose) {
             System.out.println("RemappedRuntimeInheritanceProvider getParents "+before+" -> "+after);
@@ -48,7 +55,7 @@ public class RemappedRuntimeInheritanceProvider extends RuntimeInheritanceProvid
         // Un-remap the output (example: obf -> cb)
         List<String> afterParents = new ArrayList<String>();
         for (String beforeParent : beforeParents) {
-            String afterParent = JarRemapper.mapTypeName(beforeParent, inverseJarMapping.packages, inverseJarMapping.classes);
+            String afterParent = JarRemapper.mapTypeName(beforeParent, inverseJarMapping.packages, inverseJarMapping.classes, beforeParent);
             if (verbose) {
                 System.out.println("- " + beforeParent + " -> " + afterParent);
             }