diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1dd8c5674f..086b666cc1 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -9051,7 +9051,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)
 	values[4] = _(conf->short_desc);
 
 	/* extra_desc */
-	values[5] = _(conf->long_desc);
+	values[5] = conf->long_desc != NULL ? _(conf->long_desc) : NULL;
 
 	/* context */
 	values[6] = GucContext_Names[conf->context];