diff --git a/source/platform/posix/unix/gtk_dialogs.cpp b/source/platform/posix/unix/gtk_dialogs.cpp
index 48f8c06fc..a7171eba0 100644
--- a/source/platform/posix/unix/gtk_dialogs.cpp
+++ b/source/platform/posix/unix/gtk_dialogs.cpp
@@ -59,6 +59,7 @@ typedef enum
 #include "i_system.h"
 #include "version.h"
 #include "gamecontrol.h"
+#include "cmdlib.h"
 
 EXTERN_CVAR (Bool, queryiwad);