diff --git a/lib/CodeGen/CGVtable.h b/lib/CodeGen/CGVtable.h
index af718b3..1d98bed 100644
--- a/lib/CodeGen/CGVtable.h
+++ b/lib/CodeGen/CGVtable.h
@@ -17,6 +17,10 @@
 #include "llvm/ADT/DenseMap.h"
 #include "GlobalDecl.h"
 
+namespace llvm {
+  class Constant;
+}
+
 namespace clang {
   class CXXMethodDecl;
   class CXXRecordDecl;