diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index ef50899..ce53fc2 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -1011,6 +1011,12 @@
   assert(false && "Don't know how to mangle TemplateTypeParmTypes yet!");
 }
 
+void MicrosoftCXXNameMangler::mangleType(
+                                       const SubstTemplateTypeParmPackType *T) {
+  assert(false && 
+         "Don't know how to mangle SubstTemplateTypeParmPackTypes yet!");
+}
+
 // <type> ::= <pointer-type>
 // <pointer-type> ::= <pointer-cvr-qualifiers> <cvr-qualifiers> <type>
 void MicrosoftCXXNameMangler::mangleType(const PointerType *T) {