diff --git a/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp b/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp
--- a/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp
+++ b/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp
@@ -165,7 +165,7 @@
 
 private:
   bool appendUnderscores;
-  bool usePassOpt;
+  bool usePassOpt = false;
 };
 } // namespace