diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index 720f7bb..9a679ee 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -671,9 +671,8 @@
   
   Invocation->getDiagnosticOpts().VerifyDiagnostics = 0;
   
-  // FIXME: Strip away all of the compilation options that won't be transferred
-  // down to the module. This presumably includes -D flags, optimization 
-  // settings, etc.
+  assert(ImportingInstance.getInvocation().getModuleHash() ==
+           Invocation->getModuleHash() && "Module hash mismatch!");
   
   // Construct a compiler instance that will be used to actually create the
   // module.