diff --git a/siputils.py b/siputils.py
index 42bd72f..7521b77 100644
--- a/siputils.py
+++ b/siputils.py
@@ -536,7 +536,7 @@ class Makefile:
                 defines.append("QT_DLL")
 
             if not self._debug:
-                defines.append("QT_NO_DEBUG")
+                defines.append("TQT_NO_DEBUG")
 
             if self.config.qt_version >= 0x040000:
                 for mod in self._qt: