diff --git a/src/backend/catalog/pg_proc.c b/src/backend/catalog/pg_proc.c
index 1454d2fb67..ae9df20103 100644
--- a/src/backend/catalog/pg_proc.c
+++ b/src/backend/catalog/pg_proc.c
@@ -752,6 +752,7 @@ fmgr_internal_validator(PG_FUNCTION_ARGS)
 						prosrc)));
 
 	ReleaseSysCache(tuple);
+	pfree(prosrc);
 
 	PG_RETURN_VOID();
 }