diff --git lib/CodeGen/CGExprScalar.cpp lib/CodeGen/CGExprScalar.cpp
index 08c81c0..998b688 100644
--- lib/CodeGen/CGExprScalar.cpp
+++ lib/CodeGen/CGExprScalar.cpp
@@ -1215,7 +1215,13 @@ Value *ScalarExprEmitter::VisitInitListExpr(InitListExpr *E) {
           Value *LHS = nullptr, *RHS = nullptr;
           if (CurIdx == 0) {
             // insert into undef -> shuffle (src, undef)
-            Args.push_back(C);
+            // extractelement index can be any integer type
+            // shufflemask is only allowed to contain 32 bit integers
+            // make sure we can savely convert to 32 bit
+            assert(llvm::ConstantInt::isValueValidForType(CGF.Int32Ty,
+                                                          C->getZExtValue()) &&
+                   "Index operand too large for shufflevector mask!");
+            Args.push_back(Builder.getInt32(C->getZExtValue()));
             Args.resize(ResElts, llvm::UndefValue::get(CGF.Int32Ty));

             LHS = EI->getVectorOperand();