diff --git a/Source/driver/Castro.H b/Source/driver/Castro.H
index b0882ec2d0..a3c6983c4a 100644
--- a/Source/driver/Castro.H
+++ b/Source/driver/Castro.H
@@ -1341,7 +1341,7 @@ protected:
 ///
 /// Flag for indicating that we want to save prev_state until the reflux.
 ///
-    bool keep_prev_state;
+    bool keep_prev_state{};
 
 
 #ifdef TRUE_SDC