diff --git a/oss-fuzz/config/mruby_fuzzer.options b/oss-fuzz/config/mruby_fuzzer.options
index 5d1c8d2da..132affcae 100644
--- a/oss-fuzz/config/mruby_fuzzer.options
+++ b/oss-fuzz/config/mruby_fuzzer.options
@@ -1,3 +1,5 @@
 [libfuzzer]
-close_fd_mask=3
-dict=mruby.dict
+close_fd_mask = 3
+dict = mruby.dict
+fork = 8
+only_ascii = 1