diff --git a/mlir/lib/Transforms/DialectConversion.cpp b/mlir/lib/Transforms/DialectConversion.cpp
index 333214efcc05..66474348ca22 100644
--- a/mlir/lib/Transforms/DialectConversion.cpp
+++ b/mlir/lib/Transforms/DialectConversion.cpp
@@ -171,11 +171,14 @@ struct DialectConversionRewriter final : public PatternRewriter {
   void replaceOp(Operation *op, ArrayRef<Value *> newValues,
                  ArrayRef<Value *> valuesToRemoveIfDead) override {
     assert(newValues.size() == op->getNumResults());
-    // Create mappings for any type changes.
-    for (unsigned i = 0, e = newValues.size(); i < e; ++i)
-      if (newValues[i] &&
-          op->getResult(i)->getType() != newValues[i]->getType())
+
+    // Create mappings for each of the new result values.
+    for (unsigned i = 0, e = newValues.size(); i < e; ++i) {
+      assert((newValues[i] || op->getResult(i)->use_empty()) &&
+             "result value has remaining uses that must be replaced");
+      if (newValues[i])
         mapping.map(op->getResult(i), newValues[i]);
+    }
 
     // Record the requested operation replacement.
     replacements.emplace_back(op, newValues);