diff --git a/include/wx/unix/apptbase.h b/include/wx/unix/apptbase.h
index 0f77452390..153d65c735 100644
--- a/include/wx/unix/apptbase.h
+++ b/include/wx/unix/apptbase.h
@@ -14,7 +14,6 @@
 
 struct wxEndProcessData;
 struct wxExecuteData;
-class wxPipe;
 
 // ----------------------------------------------------------------------------
 // wxAppTraits: the Unix version adds extra hooks needed by Unix code