diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 6b4db305e5..d4d74baedb 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -8503,7 +8503,7 @@ static Size
 estimate_variable_size(struct config_generic * gconf)
 {
 	Size		size;
-	Size		valsize;
+	Size		valsize = 0;
 
 	if (can_skip_gucvar(gconf))
 		return 0;