diff --git a/service.c b/service.c
index bab34c09..e9b36c08 100644
--- a/service.c
+++ b/service.c
@@ -24,6 +24,7 @@
 
 #include "config.h"		/* Generated by configure script */
 
+#include <ctype.h>		/* isblank() */
 #include <sched.h>
 #include <string.h>
 #include <sys/wait.h>