diff --git a/test/common/router/header_parser_corpus/clusterfuzz-testcase-minimized-header_parser_fuzz_test-5630125928873984 b/test/common/router/header_parser_corpus/clusterfuzz-testcase-minimized-header_parser_fuzz_test-5630125928873984
new file mode 100644
index 000000000000..51cef79477d3
--- /dev/null
+++ b/test/common/router/header_parser_corpus/clusterfuzz-testcase-minimized-header_parser_fuzz_test-5630125928873984
@@ -0,0 +1 @@
+headers_to_add {   header {     key: " "     value: "%START_TIME(�)%"   } } request_info {   start_time: 72059116831228591 }
diff --git a/test/fuzz/utility.h b/test/fuzz/utility.h
index 4536ae49bb08..f50659e0c3f2 100644
--- a/test/fuzz/utility.h
+++ b/test/fuzz/utility.h
@@ -36,7 +36,13 @@ inline test::fuzz::Headers toHeaders(const Http::HeaderMap& headers) {
 inline TestRequestInfo fromRequestInfo(const test::fuzz::RequestInfo& request_info) {
   TestRequestInfo test_request_info;
   test_request_info.metadata_ = request_info.dynamic_metadata();
-  test_request_info.start_time_ = SystemTime(std::chrono::microseconds(request_info.start_time()));
+#ifdef __APPLE__
+  // Clocks don't track at nanosecond on OS X.
+  test_request_info.start_time_ =
+      SystemTime(std::chrono::microseconds(request_info.start_time() / 1000));
+#else
+  test_request_info.start_time_ = SystemTime(std::chrono::nanoseconds(request_info.start_time()));
+#endif
   if (request_info.has_response_code()) {
     test_request_info.response_code_ = request_info.response_code().value();
   }