--- a/daemon/gamemode-context.c
+++ b/daemon/gamemode-context.c
@@ -50,6 +50,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <sys/time.h>
 #include <systemd/sd-daemon.h> /* TODO: Move usage to gamemode-dbus.c */
 #include <unistd.h>
+#include <signal.h>
 
 /**
  * The GameModeClient encapsulates the remote connection, providing a list