diff --git a/lib/modules/Thread.pmod b/lib/modules/Thread.pmod
index 06c5052a974c3d1fcad14b3d60627800da6c1214..a7b34cbb90e8781907333e5ac0b5d7822417cf62 100644
--- a/lib/modules/Thread.pmod
+++ b/lib/modules/Thread.pmod
@@ -879,8 +879,9 @@ optional class Farm
 //!   @[ResourceCount], @[MutexKey]
 //!
 optional class ResourceCountKey {
-
-  private inherit __builtin.DestructImmediate;
+#if constant(Pike.DestructImmediate)
+  private inherit Pike.DestructImmediate;
+#endif
 
   /*semi*/private ResourceCount parent;