diff --git a/src/core/display.c b/src/core/display.c
index ad9d13a30..9fedf0a8e 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -72,6 +72,7 @@
 #include <X11/extensions/Xdamage.h>
 #include <X11/extensions/Xfixes.h>
 #include <string.h>
+#include <unistd.h>
 
 #define GRAB_OP_IS_WINDOW_SWITCH(g)                     \
         (g == META_GRAB_OP_KEYBOARD_TABBING_NORMAL  ||  \