diff --git a/mlir/include/mlir/Tools/mlir-opt/MlirOptMain.h b/mlir/include/mlir/Tools/mlir-opt/MlirOptMain.h
index c3ac9d99c24bf..7b83f10573645 100644
--- a/mlir/include/mlir/Tools/mlir-opt/MlirOptMain.h
+++ b/mlir/include/mlir/Tools/mlir-opt/MlirOptMain.h
@@ -264,7 +264,7 @@ class MlirOptMainConfig {
   bool allowUnregisteredDialectsFlag = false;
 
   /// Remark format
-  RemarkFormat remarkFormatFlag;
+  RemarkFormat remarkFormatFlag = REMARK_FORMAT_STDOUT;
   /// Remark file to output to
   std::string remarksOutputFileFlag = "";
   /// Remark filters