diff --git a/utils/TableGen/CodeGenDAGPatterns.cpp b/utils/TableGen/CodeGenDAGPatterns.cpp
index 00bc9a5bbb9..2602bbcf6f6 100644
--- a/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -2119,9 +2119,11 @@ InferAllTypes(const StringMap<SmallVector<TreePatternNode*,1> > *InNamedTypes) {
       // If we have input named node types, propagate their types to the named
       // values here.
       if (InNamedTypes) {
-        // FIXME: Should be error?
-        assert(InNamedTypes->count(I->getKey()) &&
-               "Named node in output pattern but not input pattern?");
+        if (!InNamedTypes->count(I->getKey())) {
+          error("Node '" + std::string(I->getKey()) +
+                "' in output pattern but not input pattern");
+          return true;
+        }
 
         const SmallVectorImpl<TreePatternNode*> &InNodes =
           InNamedTypes->find(I->getKey())->second;