diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index e122df9..0d6f6e6 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -74,12 +74,14 @@
     if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(*P)) {
       ID.AddInteger(1);
       ID.AddBoolean(NTTP->isParameterPack());
-      ID.AddPointer(NTTP->getType().getAsOpaquePtr());
+      ID.AddPointer(NTTP->getType().getCanonicalType().getAsOpaquePtr());
       if (NTTP->isExpandedParameterPack()) {
         ID.AddBoolean(true);
         ID.AddInteger(NTTP->getNumExpansionTypes());
-        for (unsigned I = 0, N = NTTP->getNumExpansionTypes(); I != N; ++I)
-          ID.AddPointer(NTTP->getExpansionType(I).getAsOpaquePtr());
+        for (unsigned I = 0, N = NTTP->getNumExpansionTypes(); I != N; ++I) {
+          QualType T = NTTP->getExpansionType(I);
+          ID.AddPointer(T.getCanonicalType().getAsOpaquePtr());
+        }
       } else 
         ID.AddBoolean(false);
       continue;
diff --git a/test/SemaTemplate/temp_arg_template.cpp b/test/SemaTemplate/temp_arg_template.cpp
index 9c34089..106111e 100644
--- a/test/SemaTemplate/temp_arg_template.cpp
+++ b/test/SemaTemplate/temp_arg_template.cpp
@@ -54,3 +54,9 @@
 
   void f0( Y<int,1> y){ 1 << y; } // expected-note{{in instantiation of function template specialization 'N::operator<<<Y, int, 1>' requested here}}
 }
+
+// PR12179
+template <typename Primitive, template <Primitive...> class F>
+struct unbox_args {
+  typedef typename Primitive::template call<F> x;
+};