1 files changed, 2 insertions, 0 deletions
diff --git a/rts/sm/NonMovingSweep.c b/rts/sm/NonMovingSweep.c
index cf5fcd70d7..b390959612 100644
--- a/rts/sm/NonMovingSweep.c
+++ b/rts/sm/NonMovingSweep.c
@@ -307,9 +307,11 @@ static void freeChain_lock_max(bdescr *bd, int max_dur)
     freeGroup(bd);
     bd = next_bd;
     if (i == max_dur) {
+#if defined(THREADED_RTS)
         RELEASE_SM_LOCK;
         yieldThread();
         ACQUIRE_SM_LOCK;
+#endif
         i = 0;
     }
     i++;