diff --git a/osx/config.h b/osx/config.h
index ef55f845b..edceac4cd 100644
--- a/osx/config.h
+++ b/osx/config.h
@@ -20,6 +20,9 @@
 /* Define to 1 if you have the <execinfo.h> header file. */
 #define HAVE_EXECINFO_H 1
 
+/* Define to 1 if you have the `flock' function. */
+#define HAVE_FLOCK 1
+
 /* Define to 1 if you have the `futimens' function. */
 /* #undef HAVE_FUTIMENS */