diff --git a/mlir/lib/Dialect/Async/IR/Async.cpp b/mlir/lib/Dialect/Async/IR/Async.cpp
--- a/mlir/lib/Dialect/Async/IR/Async.cpp
+++ b/mlir/lib/Dialect/Async/IR/Async.cpp
@@ -101,12 +101,17 @@
   // Get the underlying value types from async values returned from the
   // parent `async.execute` operation.
   auto executeOp = op.getParentOfType<ExecuteOp>();
+
+  if (executeOp.results().size() != op.getNumOperands())
+    return op.emitOpError("number of operands does not match the number of"
+                          "values returned from the parent ExecuteOp");
+
   auto types = llvm::map_range(executeOp.results(), [](const OpResult &result) {
     return result.getType().cast<ValueType>().getValueType();
   });
 
   if (!std::equal(types.begin(), types.end(), op.getOperandTypes().begin()))
-    return op.emitOpError("Operand types do not match the types returned from "
+    return op.emitOpError("operand types do not match the types returned from "
                           "the parent ExecuteOp");
 
   return success();