diff --git a/src/shrpx.cc b/src/shrpx.cc
index 24290891..ee05263b 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -2111,7 +2111,7 @@ void process_options(
 
     DownstreamAddrGroup g(StringRef::from_lit("/"));
     g.addrs.push_back(std::move(addr));
-    mod_config()->router.add_route(g.pattern.c_str(), 1, addr_groups.size());
+    mod_config()->router.add_route(StringRef{g.pattern}, addr_groups.size());
     addr_groups.push_back(std::move(g));
   } else if (get_config()->http2_proxy || get_config()->client_proxy) {
     // We don't support host mapping in these cases.  Move all
@@ -2124,7 +2124,7 @@ void process_options(
     std::vector<DownstreamAddrGroup>().swap(addr_groups);
     // maybe not necessary?
     mod_config()->router = Router();
-    mod_config()->router.add_route(catch_all.pattern.c_str(), 1,
+    mod_config()->router.add_route(StringRef{catch_all.pattern},
                                    addr_groups.size());
     addr_groups.push_back(std::move(catch_all));
   }
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 23b480b3..9dd5c444 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -609,8 +609,7 @@ void parse_mapping(const DownstreamAddr &addr, const char *src) {
     DownstreamAddrGroup g(StringRef{pattern});
     g.addrs.push_back(addr);
 
-    mod_config()->router.add_route(g.pattern.c_str(), g.pattern.size(),
-                                   addr_groups.size());
+    mod_config()->router.add_route(StringRef{g.pattern}, addr_groups.size());
 
     addr_groups.push_back(std::move(g));
   }
diff --git a/src/shrpx_config_test.cc b/src/shrpx_config_test.cc
index fa8c1391..53b1bc30 100644
--- a/src/shrpx_config_test.cc
+++ b/src/shrpx_config_test.cc
@@ -256,7 +256,7 @@ void test_shrpx_config_match_downstream_addr_group(void) {
 
   for (size_t i = 0; i < groups.size(); ++i) {
     auto &g = groups[i];
-    router.add_route(g.pattern.c_str(), g.pattern.size(), i);
+    router.add_route(StringRef{g.pattern}, i);
   }
 
   CU_ASSERT(0 == match_downstream_addr_group(router, "nghttp2.org", "/", groups,
diff --git a/src/shrpx_router.cc b/src/shrpx_router.cc
index e0404252..4324748a 100644
--- a/src/shrpx_router.cc
+++ b/src/shrpx_router.cc
@@ -66,21 +66,21 @@ void Router::add_node(RNode *node, const char *pattern, size_t patlen,
   add_next_node(node, std::move(new_node));
 }
 
-bool Router::add_route(const char *pattern, size_t patlen, size_t index) {
+bool Router::add_route(const StringRef &pattern, size_t index) {
   auto node = &root_;
   size_t i = 0;
 
   for (;;) {
     auto next_node = find_next_node(node, pattern[i]);
     if (next_node == nullptr) {
-      add_node(node, pattern + i, patlen - i, index);
+      add_node(node, pattern.c_str() + i, pattern.size() - i, index);
       return true;
     }
 
     node = next_node;
 
-    auto slen = patlen - i;
-    auto s = pattern + i;
+    auto slen = pattern.size() - i;
+    auto s = pattern.c_str() + i;
     auto n = std::min(node->len, slen);
     size_t j;
     for (j = 0; j < n && node->s[j] == s[j]; ++j)
@@ -125,8 +125,8 @@ bool Router::add_route(const char *pattern, size_t patlen, size_t index) {
 
     i += j;
 
-    assert(patlen > i);
-    add_node(node, pattern + i, patlen - i, index);
+    assert(pattern.size() > i);
+    add_node(node, pattern.c_str() + i, pattern.size() - i, index);
 
     return true;
   }
diff --git a/src/shrpx_router.h b/src/shrpx_router.h
index 07aadf69..e4d9a465 100644
--- a/src/shrpx_router.h
+++ b/src/shrpx_router.h
@@ -55,8 +55,8 @@ struct RNode {
 class Router {
 public:
   Router();
-  // Adds route |pattern| of size |patlen| with its |index|.
-  bool add_route(const char *pattern, size_t patlen, size_t index);
+  // Adds route |pattern| with its |index|.
+  bool add_route(const StringRef &pattern, size_t index);
   // Returns the matched index of pattern.  -1 if there is no match.
   ssize_t match(const std::string &host, const char *path,
                 size_t pathlen) const;