diff --git a/src/shrpx.cc b/src/shrpx.cc
index 33272f97..44c4094e 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -1067,8 +1067,7 @@ void fill_default_config() {
     auto &ocspconf = tlsconf.ocsp;
     // ocsp update interval = 14400 secs = 4 hours, borrowed from h2o
     ocspconf.update_interval = 4_h;
-    ocspconf.fetch_ocsp_response_file =
-        strcopy(PKGDATADIR "/fetch-ocsp-response");
+    ocspconf.fetch_ocsp_response_file = PKGDATADIR "/fetch-ocsp-response";
   }
 
   {
@@ -1579,8 +1578,8 @@ SSL/TLS:
   --fetch-ocsp-response-file=<PATH>
               Path to  fetch-ocsp-response script file.  It  should be
               absolute path.
-              Default: )"
-      << get_config()->tls.ocsp.fetch_ocsp_response_file.get() << R"(
+              Default: )" << get_config()->tls.ocsp.fetch_ocsp_response_file
+      << R"(
   --ocsp-update-interval=<DURATION>
               Set interval to update OCSP response cache.
               Default: )"
@@ -2094,10 +2093,10 @@ void process_options(
 
   if (!upstreamconf.no_tls && !tlsconf.ocsp.disabled) {
     struct stat buf;
-    if (stat(tlsconf.ocsp.fetch_ocsp_response_file.get(), &buf) != 0) {
+    if (stat(tlsconf.ocsp.fetch_ocsp_response_file.c_str(), &buf) != 0) {
       tlsconf.ocsp.disabled = true;
       LOG(WARN) << "--fetch-ocsp-response-file: "
-                << tlsconf.ocsp.fetch_ocsp_response_file.get()
+                << tlsconf.ocsp.fetch_ocsp_response_file
                 << " not found.  OCSP stapling has been disabled.";
     }
   }
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 20d30c86..6afcc47b 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -2086,7 +2086,7 @@ int parse_config(const char *opt, const char *optarg,
     return parse_uint(&mod_config()->http2.downstream.connections_per_worker,
                       opt, optarg);
   case SHRPX_OPTID_FETCH_OCSP_RESPONSE_FILE:
-    mod_config()->tls.ocsp.fetch_ocsp_response_file = strcopy(optarg);
+    mod_config()->tls.ocsp.fetch_ocsp_response_file = optarg;
 
     return 0;
   case SHRPX_OPTID_OCSP_UPDATE_INTERVAL:
diff --git a/src/shrpx_config.h b/src/shrpx_config.h
index e5a21241..d290a37a 100644
--- a/src/shrpx_config.h
+++ b/src/shrpx_config.h
@@ -394,7 +394,7 @@ struct TLSConfig {
   // OCSP realted configurations
   struct {
     ev_tstamp update_interval;
-    std::unique_ptr<char[]> fetch_ocsp_response_file;
+    ImmutableString fetch_ocsp_response_file;
     bool disabled;
   } ocsp;
 
diff --git a/src/shrpx_connection_handler.cc b/src/shrpx_connection_handler.cc
index 588e814b..8dea4f38 100644
--- a/src/shrpx_connection_handler.cc
+++ b/src/shrpx_connection_handler.cc
@@ -463,7 +463,8 @@ int ConnectionHandler::start_ocsp_update(const char *cert_file) {
   assert(!ev_is_active(&ocsp_.chldev));
 
   char *const argv[] = {
-      const_cast<char *>(get_config()->tls.ocsp.fetch_ocsp_response_file.get()),
+      const_cast<char *>(
+          get_config()->tls.ocsp.fetch_ocsp_response_file.c_str()),
       const_cast<char *>(cert_file), nullptr};
   char *const envp[] = {nullptr};