diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 22740ce..1e71e3b 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -3991,9 +3991,9 @@ mdb_env_map(MDB_env *env, void *addr)
 		 * and won't map more than the file size.
 		 * Just set the maxsize right now.
 		 */
-		if (SetFilePointer(env->me_fd, sizelo, &sizehi, 0) != (DWORD)sizelo
+		if (!(flags & MDB_WRITEMAP) && (SetFilePointer(env->me_fd, sizelo, &sizehi, 0) != (DWORD)sizelo
 			|| !SetEndOfFile(env->me_fd)
-			|| SetFilePointer(env->me_fd, 0, NULL, 0) != 0)
+			|| SetFilePointer(env->me_fd, 0, NULL, 0) != 0))
 			return ErrCode();
 	}