diff --git a/src/lock.c b/src/lock.c
index c88fc662..3a352b92 100644
--- a/src/lock.c
+++ b/src/lock.c
@@ -18,6 +18,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/file.h>