diff --git a/gdk/x11/gdkdevice-core-x11.c b/gdk/x11/gdkdevice-core-x11.c
index d4d10f1738..8cd0408661 100644
--- a/gdk/x11/gdkdevice-core-x11.c
+++ b/gdk/x11/gdkdevice-core-x11.c
@@ -29,9 +29,6 @@
 
 #include <math.h>
 
-/* for the use of round() */
-#include "fallback-c89.c"
-
 struct _GdkX11DeviceCore
 {
   GdkDevice parent_instance;
diff --git a/gdk/x11/gdkdevice-xi2.c b/gdk/x11/gdkdevice-xi2.c
index b7f676e507..98d3ce38a5 100644
--- a/gdk/x11/gdkdevice-xi2.c
+++ b/gdk/x11/gdkdevice-xi2.c
@@ -32,9 +32,6 @@
 
 #include <math.h>
 
-/* for the use of round() */
-#include "fallback-c89.c"
-
 typedef struct _ScrollValuator ScrollValuator;
 
 struct _ScrollValuator