diff --git a/pseudoramiX/pseudoramiX.h b/pseudoramiX/pseudoramiX.h
index 5393062ee..e7b255336 100644
--- a/pseudoramiX/pseudoramiX.h
+++ b/pseudoramiX/pseudoramiX.h
@@ -2,7 +2,12 @@
  * Minimal implementation of PanoramiX/Xinerama
  */
 
+#ifndef XSERVER_PSEUDORAMIX_H
+#define XSERVER_PSEUDORAMIX_H
+
 void
 PseudoramiXAddScreen(int x, int y, int w, int h);
 void
 PseudoramiXResetScreens(void);
+
+#endif /* XSERVER_PSEUDORAMIX_H */