diff --git a/desmume/src/frontend/posix/gtk-glade/main.cpp b/desmume/src/frontend/posix/gtk-glade/main.cpp
index 4b16980b3..796bfb0d6 100644
--- a/desmume/src/frontend/posix/gtk-glade/main.cpp
+++ b/desmume/src/frontend/posix/gtk-glade/main.cpp
@@ -21,6 +21,8 @@
  * Boston, MA 02111-1307, USA.
  */
 
+#include <X11/Xlib.h>
+
 #include "callbacks.h"
 #include "callbacks_IO.h"
 #include "dTools/callbacks_dtools.h"
diff --git a/desmume/src/frontend/posix/gtk/main.cpp b/desmume/src/frontend/posix/gtk/main.cpp
index 7216798ab..a7fc2cba2 100644
--- a/desmume/src/frontend/posix/gtk/main.cpp
+++ b/desmume/src/frontend/posix/gtk/main.cpp
@@ -28,6 +28,7 @@
 #include <gtk/gtk.h>
 #include <gdk/gdkkeysyms.h>
 #include <SDL.h>
+#include <X11/Xlib.h>
 
 #include "types.h"
 #include "firmware.h"