diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index d3d771b..0400b4c 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -503,6 +503,10 @@
   for (TemplateSpecializationType::iterator Arg = T->begin(), ArgEnd = T->end();
        Arg != ArgEnd; ++Arg) {
     switch (Arg->getKind()) {
+    case TemplateArgument::Null:
+      assert(false && "Should never have a NULL template argument");
+      break;
+        
     case TemplateArgument::Type: {
       QualType T = SemaRef.InstantiateType(Arg->getAsType(), 
                                            TemplateArgs,