diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index c8c687d6f51..416cbd60909 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3674,6 +3674,11 @@ check_restrict_nonsystem_relation_kind(char **newval, void **extra, GucSource so
 
 	/* Save the flags in *extra, for use by the assign function */
 	*extra = malloc(sizeof(int));
+	if (*extra == NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+
 	*((int *) *extra) = flags;
 
 	return true;