diff --git a/llvm/include/llvm/CodeGen/ValueTypes.h b/llvm/include/llvm/CodeGen/ValueTypes.h
index 888b83d6f736ff..ccdaab5ed96d27 100644
--- a/llvm/include/llvm/CodeGen/ValueTypes.h
+++ b/llvm/include/llvm/CodeGen/ValueTypes.h
@@ -100,8 +100,11 @@ namespace llvm {
     /// Return a VT for a vector type whose attributes match ourselves
     /// with the exception of the element type that is chosen by the caller.
     EVT changeVectorElementType(EVT EltVT) const {
-      if (isSimple() && EltVT.isSimple())
+      if (isSimple()) {
+        assert(EltVT.isSimple() &&
+               "Can't change simple vector VT to have extended element VT");
         return getSimpleVT().changeVectorElementType(EltVT.getSimpleVT());
+      }
       return changeExtendedVectorElementType(EltVT);
     }
 
diff --git a/llvm/lib/CodeGen/ValueTypes.cpp b/llvm/lib/CodeGen/ValueTypes.cpp
index 7e4c4b1c634e1c..7f38420b83703f 100644
--- a/llvm/lib/CodeGen/ValueTypes.cpp
+++ b/llvm/lib/CodeGen/ValueTypes.cpp
@@ -15,11 +15,13 @@
 using namespace llvm;
 
 EVT EVT::changeExtendedTypeToInteger() const {
+  assert(isExtended() && "Type is not extended!");
   LLVMContext &Context = LLVMTy->getContext();
   return getIntegerVT(Context, getSizeInBits());
 }
 
 EVT EVT::changeExtendedVectorElementTypeToInteger() const {
+  assert(isExtended() && "Type is not extended!");
   LLVMContext &Context = LLVMTy->getContext();
   EVT IntTy = getIntegerVT(Context, getScalarSizeInBits());
   return getVectorVT(Context, IntTy, getVectorNumElements(),
@@ -27,6 +29,7 @@ EVT EVT::changeExtendedVectorElementTypeToInteger() const {
 }
 
 EVT EVT::changeExtendedVectorElementType(EVT EltVT) const {
+  assert(isExtended() && "Type is not extended!");
   LLVMContext &Context = LLVMTy->getContext();
   return getVectorVT(Context, EltVT, getVectorElementCount());
 }