diff --git a/runtime/internal/clite/pthread/sync/sync_darwin_amd64.go b/runtime/internal/clite/pthread/sync/sync_darwin_amd64.go
index 0cbe29cb..4b0e3dba 100644
--- a/runtime/internal/clite/pthread/sync/sync_darwin_amd64.go
+++ b/runtime/internal/clite/pthread/sync/sync_darwin_amd64.go
@@ -2,7 +2,7 @@ package sync
 
 const (
 	PthreadOnceSize       = 16
-	PthreadMutexSize      = 56
+	PthreadMutexSize      = 64
 	PthreadMutexAttrSize  = 8
 	PthreadCondSize       = 40
 	PthreadCondAttrSize   = 8