diff --git a/src/api_manager/config_test.cc b/src/api_manager/config_test.cc
index 68bc420df..9053193da 100644
--- a/src/api_manager/config_test.cc
+++ b/src/api_manager/config_test.cc
@@ -479,15 +479,23 @@ static const char backends_config[] =
     "name: \"backends-config\"\n"
     "backend {\n"
     "  rules {\n"
-    "    selector: \"test.api.MethodWithBackend\"\n"
+    "    selector: \"test.api.MethodWithBackendConstant\"\n"
     "    address: \"TestBackend:TestPort\"\n"
     "    path_translation: CONSTANT_ADDRESS\n"
     "  }\n"
+    "  rules {\n"
+    "    selector: \"test.api.MethodWithBackendAppend\"\n"
+    "    address: \"TestBackend:TestPort\"\n"
+    "    path_translation: APPEND_PATH_TO_ADDRESS\n"
+    "  }\n"
     "}\n"
     "apis {\n"
     "  name: \"test.api\"\n"
     "  methods {\n"
-    "    name: \"MethodWithBackend\"\n"
+    "    name: \"MethodWithBackendConstant\"\n"
+    "  }\n"
+    "  methods {\n"
+    "    name: \"MethodWithBackendAppend\"\n"
     "  }\n"
     "  methods {\n"
     "    name: \"MethodWithoutBackend\"\n"
@@ -501,11 +509,19 @@ TEST(Config, LoadBackends) {
   ASSERT_TRUE(config);
 
   const MethodInfo *method_with_backend =
-      config->GetMethodInfo("POST", "/test.api/MethodWithBackend");
+      config->GetMethodInfo("POST", "/test.api/MethodWithBackendConstant");
   ASSERT_NE(nullptr, method_with_backend);
   EXPECT_EQ("TestBackend:TestPort", method_with_backend->backend_address());
+  EXPECT_EQ("/", method_with_backend->backend_path());
   EXPECT_EQ(1, method_with_backend->backend_path_translation());
 
+  method_with_backend =
+      config->GetMethodInfo("POST", "/test.api/MethodWithBackendAppend");
+  ASSERT_NE(nullptr, method_with_backend);
+  EXPECT_EQ("TestBackend:TestPort", method_with_backend->backend_address());
+  EXPECT_EQ("", method_with_backend->backend_path());
+  EXPECT_EQ(2, method_with_backend->backend_path_translation());
+
   const MethodInfo *method_without_backend =
       config->GetMethodInfo("POST", "/test.api/MethodWithoutBackend");
   ASSERT_NE(nullptr, method_without_backend);
diff --git a/src/api_manager/method_impl.cc b/src/api_manager/method_impl.cc
index 8cc4b87b9..bfb7dd1a8 100644
--- a/src/api_manager/method_impl.cc
+++ b/src/api_manager/method_impl.cc
@@ -134,6 +134,14 @@ void MethodInfoImpl::process_backend_rule(
     backend_path_ = backend_address_.substr(i);
     backend_address_ = backend_address_.substr(0, i);
   }
+
+  // For constant_address, backend_path should not be empty.
+  // An empty backend_path should be treated as "/".
+  if (backend_path_.empty() &&
+      backend_path_translation_ ==
+          ::google::api::BackendRule_PathTranslation_CONSTANT_ADDRESS) {
+    backend_path_ = "/";
+  }
 }
 
 void MethodInfoImpl::process_system_parameters() {
diff --git a/src/api_manager/method_test.cc b/src/api_manager/method_test.cc
index 7ea6a3454..5f5452d44 100644
--- a/src/api_manager/method_test.cc
+++ b/src/api_manager/method_test.cc
@@ -156,7 +156,7 @@ TEST(MethodInfo, PreservesBackendAddress_Constant2) {
   method_info->process_backend_rule(rule);
   ASSERT_EQ(method_info->backend_address(),
             "http://example.cloudfunctions.net");
-  ASSERT_EQ(method_info->backend_path(), "");
+  ASSERT_EQ(method_info->backend_path(), "/");
   ASSERT_EQ(method_info->backend_jwt_audience(), "");
 }
 
@@ -168,7 +168,7 @@ TEST(MethodInfo, PreservesBackendAddress_Constant3) {
       ::google::api::BackendRule_PathTranslation_CONSTANT_ADDRESS);
   method_info->process_backend_rule(rule);
   ASSERT_EQ(method_info->backend_address(), "backend");
-  ASSERT_EQ(method_info->backend_path(), "");
+  ASSERT_EQ(method_info->backend_path(), "/");
 }
 
 TEST(MethodInfo, PreservesBackendAddress_Append) {
diff --git a/src/nginx/t/backend_routing_constant_address.t b/src/nginx/t/backend_routing_constant_address.t
index eaf1d1c55..2b6f78313 100644
--- a/src/nginx/t/backend_routing_constant_address.t
+++ b/src/nginx/t/backend_routing_constant_address.t
@@ -42,7 +42,7 @@ my $BackendPort = ApiManager::pick_port();
 my $ServiceControlPort = ApiManager::pick_port();
 my $MetadataPort = ApiManager::pick_port();
 
-my $t = Test::Nginx->new()->has(qw/http proxy/)->plan(18);
+my $t = Test::Nginx->new()->has(qw/http proxy/)->plan(20);
 
 # Save service name in the service configuration protocol buffer file.
 
@@ -77,6 +77,12 @@ backend {
     path_translation: CONSTANT_ADDRESS
     jwt_audience: "test-audience"
   }
+  rules {
+    selector: "ListAllBooks"
+    address: "http://127.0.0.1:$BackendPort"
+    path_translation: CONSTANT_ADDRESS
+    jwt_audience: "test-audience"
+  }
 }
 types {
   fields {
@@ -156,6 +162,9 @@ my $response4 = ApiManager::http_get($NginxPort,'/shelves/123/books/info/1234?ke
 # also, {foo.bar} style path is supported.
 my $response5 = ApiManager::http_get($NginxPort,'/shelves/123/books/id/1234?key=this-is-an-api-key');
 
+# Test address only has host name.
+my $response6 = ApiManager::http_get($NginxPort,'/allbooks');
+
 $t->stop_daemons();
 
 my ($response_headers1, $response_body1) = split /\r\n\r\n/, $response1, 2;
@@ -195,9 +204,15 @@ is($response_body5, <<'EOF', 'Book Info returned in the response body.');
 { "id": "1234" }
 EOF
 
+my ($response_headers6, $response_body6) = split /\r\n\r\n/, $response6, 2;
+like($response_headers6, qr/HTTP\/1\.1 200 OK/, 'Returned HTTP 200.');
+is($response_body6, <<'EOF', 'ListAllBooks returned in the response body.');
+{ "allbooks" }
+EOF
+
 # Check Authorization header is added into requests.
 my @bookstore_requests = ApiManager::read_http_stream($t, 'bookstore.log');
-is(scalar @bookstore_requests, 5, 'Bookstore received 5 requests.');
+is(scalar @bookstore_requests, 6, 'Bookstore received 6 requests.');
 
 my $request = shift @bookstore_requests;
 is($request->{headers}->{'authorization'}, 'Bearer test_audience_override',
@@ -263,6 +278,13 @@ HTTP/1.1 200 OK
 Connection: close
 
 { "id": "1234" }
+EOF
+
+  $server->on('GET', '/', <<'EOF');
+HTTP/1.1 200 OK
+Connection: close
+
+{ "allbooks" }
 EOF
 
   $server->run();
diff --git a/src/nginx/t/testdata/bookstore_allow_all_http_requests.pb.txt b/src/nginx/t/testdata/bookstore_allow_all_http_requests.pb.txt
index dc4159f0b..bbe7260bc 100644
--- a/src/nginx/t/testdata/bookstore_allow_all_http_requests.pb.txt
+++ b/src/nginx/t/testdata/bookstore_allow_all_http_requests.pb.txt
@@ -4,6 +4,10 @@ http {
     selector: "ListShelves"
     get: "/shelves"
   }
+  rules {
+    selector: "ListAllBooks"
+    get: "/allbooks"
+  }
   rules {
     selector: "CorsShelves"
     custom: {
@@ -64,6 +68,10 @@ usage {
     selector: "GetShelf"
     allow_unregistered_calls: true
   }
+  rules {
+    selector: "ListAllBooks"
+    allow_unregistered_calls: true
+  }
   rules {
     selector: "ListBooks"
     allow_unregistered_calls: false