diff --git a/kitty/child-monitor.c b/kitty/child-monitor.c
index 602d88fa6..4d4e4a787 100644
--- a/kitty/child-monitor.c
+++ b/kitty/child-monitor.c
@@ -18,6 +18,7 @@
 #include <sys/ioctl.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
+#include <signal.h>
 extern PyTypeObject Screen_Type;
 
 #define EXTRA_FDS 2