diff --git a/Userland/Libraries/LibC/fcntl.h b/Userland/Libraries/LibC/fcntl.h
index 52956b3820..5d6077cafd 100644
--- a/Userland/Libraries/LibC/fcntl.h
+++ b/Userland/Libraries/LibC/fcntl.h
@@ -97,6 +97,7 @@ int watch_file(const char* path, size_t path_length);
 #define F_RDLCK 0
 #define F_WRLCK 1
 #define F_UNLCK 2
+#define F_GETLK 5
 #define F_SETLK 6
 #define F_SETLKW 7