diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index e28b9efd8f..50f2f6df6c 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -784,6 +784,21 @@ void HChange::PrintDataTo(StringStream* stream) {
 }
 
 
+HValue* HCheckInstanceType::Canonicalize() {
+  if (check_ == IS_STRING &&
+      !value()->type().IsUninitialized() &&
+      value()->type().IsString()) {
+    return NULL;
+  }
+  if (check_ == IS_SYMBOL &&
+      value()->IsConstant() &&
+      HConstant::cast(value())->handle()->IsSymbol()) {
+    return NULL;
+  }
+  return this;
+}
+
+
 void HCheckInstanceType::GetCheckInterval(InstanceType* first,
                                           InstanceType* last) {
   ASSERT(is_interval_check());
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 599035220c..401c2e4a03 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -2003,14 +2003,7 @@ class HCheckInstanceType: public HUnaryOperation {
   virtual void Verify();
 #endif
 
-  virtual HValue* Canonicalize() {
-    if (!value()->type().IsUninitialized() &&
-        value()->type().IsString() &&
-        check_ == IS_STRING) {
-      return NULL;
-    }
-    return this;
-  }
+  virtual HValue* Canonicalize();
 
   bool is_interval_check() const { return check_ <= LAST_INTERVAL_CHECK; }
   void GetCheckInterval(InstanceType* first, InstanceType* last);