diff --git a/src/OT/Var/VARC/VARC.hh b/src/OT/Var/VARC/VARC.hh
index 6380b8bf4..b6f8aea81 100644
--- a/src/OT/Var/VARC/VARC.hh
+++ b/src/OT/Var/VARC/VARC.hh
@@ -226,7 +226,7 @@ struct VARC
     }
     void release_scratch (hb_varc_scratch_t *scratch) const
     {
-      if (!cached_scratch.cmpexch (scratch, nullptr))
+      if (!cached_scratch.cmpexch (nullptr, scratch))
       {
 	scratch->~hb_varc_scratch_t ();
 	hb_free (scratch);