warning: kill undefined function

diff --git a/src/modules/gsettings/module-gsettings.c b/src/modules/gsettings/module-gsettings.c
index 6cfac77..1500e76 100644
--- a/src/modules/gsettings/module-gsettings.c
+++ b/src/modules/gsettings/module-gsettings.c
@@ -23,6 +23,7 @@
 
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <signal.h>
 
 #include <pulsecore/core-error.h>
 #include <pulsecore/core-util.h>