diff --git a/lib/roken/roken.h.in b/lib/roken/roken.h.in
index b64d98631..8a88d6f67 100644
--- a/lib/roken/roken.h.in
+++ b/lib/roken/roken.h.in
@@ -890,6 +890,7 @@ ROKEN_LIB_FUNCTION unsigned short ROKEN_LIB_CALL bswap16(unsigned short);
  * - Fallback to system flock() if available
  * - Fallback to POSIX fcntl() locks for NFS and other filesystems
  */
+#ifndef HAVE_FLOCK
 #ifndef LOCK_SH
 #define LOCK_SH   1		/* Shared lock */
 #endif
@@ -902,6 +903,7 @@ ROKEN_LIB_FUNCTION unsigned short ROKEN_LIB_CALL bswap16(unsigned short);
 #ifndef LOCK_UN
 #define LOCK_UN   8		/* Unlock */
 #endif
+#endif /* !HAVE_FLOCK */
 
 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL rk_flock(int fd, int operation);
 #define flock(_x,_y) rk_flock(_x,_y)