diff --git a/src/compiler/operation-typer.cc b/src/compiler/operation-typer.cc
index 226faeaa82..fc774f8706 100644
--- a/src/compiler/operation-typer.cc
+++ b/src/compiler/operation-typer.cc
@@ -510,7 +510,7 @@ Type* OperationTyper::NumberToString(Type* type) {
   if (type->IsNone()) return type;
   if (type->Is(Type::NaN())) return singleton_NaN_string_;
   if (type->Is(cache_.kZeroOrMinusZero)) return singleton_zero_string_;
-  return Type::SeqString();
+  return Type::String();
 }
 
 Type* OperationTyper::NumberToUint32(Type* type) {
diff --git a/test/mjsunit/regress/regress-crbug-822284.js b/test/mjsunit/regress/regress-crbug-822284.js
new file mode 100644
index 0000000000..97a38259e3
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-822284.js
@@ -0,0 +1,22 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+function foo(a) {
+  a = "" + Math.abs(a);
+  return a.charCodeAt(0);
+}
+
+// Add '1' to the number to string table (as SeqString).
+String.fromCharCode(49);
+
+// Turn the SeqString into a ThinString via forced internalization.
+const o = {};
+o[(1).toString()] = 1;
+
+assertEquals(49, foo(1));
+assertEquals(49, foo(1));
+%OptimizeFunctionOnNextCall(foo);
+assertEquals(49, foo(1));