diff --git a/contrib/cbif.c b/contrib/cbif.c
index a62b093..e27c5d0 100644
--- a/contrib/cbif.c
+++ b/contrib/cbif.c
@@ -25,6 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #define ERR(MSG) do {                                \
     fprintf(stdout, "** error **\n");                \