diff --git a/dcopperl/DCOP.xs b/dcopperl/DCOP.xs
index e5384478..3c2f2ed7 100644
--- a/dcopperl/DCOP.xs
+++ b/dcopperl/DCOP.xs
@@ -26,6 +26,8 @@
 #undef vform
 #endif
 
+#include <cassert>
+
 #include <tqpoint.h>
 #include <tqrect.h>
 #include <tqregexp.h>