diff --git a/src/arch/arm/types.hh b/src/arch/arm/types.hh
index 0611232c42..d4e6ec0dbe 100644
--- a/src/arch/arm/types.hh
+++ b/src/arch/arm/types.hh
@@ -737,18 +737,4 @@ namespace ArmISA
 
 } // namespace ArmISA
 
-namespace std {
-
-template<>
-struct hash<ArmISA::ExtMachInst> :
-        public hash<ArmISA::ExtMachInst::__StorageType> {
-
-    size_t operator()(const ArmISA::ExtMachInst &emi) const {
-        return hash<ArmISA::ExtMachInst::__StorageType>::operator()(emi);
-    }
-
-};
-
-}
-
 #endif
diff --git a/src/base/bitunion.hh b/src/base/bitunion.hh
index 718a06838a..10fa005084 100644
--- a/src/base/bitunion.hh
+++ b/src/base/bitunion.hh
@@ -388,4 +388,20 @@ namespace BitfieldBackend
 template <typename T>
 using BitUnionBaseType = typename BitfieldBackend::BitUnionBaseType<T>::Type;
 
+namespace std
+{
+    template <typename T>
+    struct hash;
+
+    template <typename T>
+    struct hash<BitUnionType<T> > : public hash<BitUnionBaseType<T> >
+    {
+        size_t
+        operator() (const BitUnionType<T> &val) const
+        {
+            return hash<BitUnionBaseType<T> >::operator()(val);
+        }
+    };
+}
+
 #endif // __BASE_BITUNION_HH__