diff --git a/channels/chan_unistim.c b/channels/chan_unistim.c
index 37758b50d8..58ac74875b 100644
--- a/channels/chan_unistim.c
+++ b/channels/chan_unistim.c
@@ -37,6 +37,7 @@
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
 #include <sys/stat.h>
+#include <signal.h>
 
 #if defined(__CYGWIN__)
 /*