better error message
diff --git a/src/lib9/create.c b/src/lib9/create.c
index c608f90..e4e3c71 100644
--- a/src/lib9/create.c
+++ b/src/lib9/create.c
@@ -62,6 +62,7 @@
 			fl.l_len = 0;
 			if(fcntl(fd, F_SETLK, &fl) < 0){
 				close(fd);
+				werrstr("lock: %r");
 				return -1;
 			}
 		}