diff --git a/unix/pterm.c b/unix/pterm.c
index 22b9c2cd..714bef1a 100644
--- a/unix/pterm.c
+++ b/unix/pterm.c
@@ -9,6 +9,7 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
+#include <signal.h>
 #include <stdio.h>
 #include <time.h>
 #include <errno.h>