diff --git a/src/unix/utilsunx.cpp b/src/unix/utilsunx.cpp
index 589abf242a..12d1e9eb06 100644
--- a/src/unix/utilsunx.cpp
+++ b/src/unix/utilsunx.cpp
@@ -1440,7 +1440,7 @@ int wxGUIAppTraits::WaitForChild(wxExecuteData& execData)
     }
 }
 
-#if wxHAS_GENERIC_PROCESS_CALLBACK
+#ifdef wxHAS_GENERIC_PROCESS_CALLBACK
 struct wxEndProcessFDIOHandler : public wxFDIOHandler
 {
     wxEndProcessFDIOHandler(wxEndProcessData *data, int fd)