diff --git a/mlir/include/mlir/IR/FunctionSupport.h b/mlir/include/mlir/IR/FunctionSupport.h
--- a/mlir/include/mlir/IR/FunctionSupport.h
+++ b/mlir/include/mlir/IR/FunctionSupport.h
@@ -390,7 +390,7 @@
       auto argAttrRange = argAttrs.template getAsRange<DictionaryAttr>();
       result.append(argAttrRange.begin(), argAttrRange.end());
     } else {
-      result.resize(getNumArguments());
+      result.append(getNumArguments(), DictionaryAttr());
     }
   }
 
@@ -479,7 +479,7 @@
       auto argAttrRange = argAttrs.template getAsRange<DictionaryAttr>();
       result.append(argAttrRange.begin(), argAttrRange.end());
     } else {
-      result.resize(getNumResults());
+      result.append(getNumResults(), DictionaryAttr());
     }
   }