Changes

diff --git a/prd.md b/prd.md
index f07ab2a..51d69da 100644
--- a/prd.md
+++ b/prd.md
@@ -15,7 +15,7 @@ A simple self-hosted service status tracker.
 - It monitors a bunch of endpoints which are defined in the
   config file
 - Endpoints may be monitored by one of the following protocols:
-  * HTTP (check it returns 2xx status)
+  * HTTP (check it returns 2xx or 3xx status)
   * TCP or UDP port open
   * ICMP
 - Possible config snippet for endpoint:
diff --git a/src/probe.cpp b/src/probe.cpp
index 5003d97..0f6edb2 100644
--- a/src/probe.cpp
+++ b/src/probe.cpp
@@ -157,7 +157,7 @@ mw::E<ProbeStatus> check(const HttpEndpoint& config,
     {
         return ProbeStatus::BAD;
     }
-    return response->status >= 200 && response->status < 300
+    return response->status >= 200 && response->status < 400
         ? ProbeStatus::GOOD : ProbeStatus::BAD;
 }
 
diff --git a/src/probe.h b/src/probe.h
index 4b7146b..d9a336b 100644
--- a/src/probe.h
+++ b/src/probe.h
@@ -9,7 +9,7 @@
 
 #include "probe_status.h"
 
-/// HTTP configuration; only a direct 2xx response is healthy.
+/// HTTP configuration; direct 2xx and 3xx responses are healthy.
 struct HttpEndpoint
 {
     /// HTTP or HTTPS URL, after applying any service URL fallback.
diff --git a/tests/probe_test.cpp b/tests/probe_test.cpp
index aa7ea34..d3076d5 100644
--- a/tests/probe_test.cpp
+++ b/tests/probe_test.cpp
@@ -286,7 +286,7 @@ TEST_F(ProbeTest, RefusedTcpAndHttp)
 TEST_F(ProbeTest, HttpStatusCodes)
 {
     ASSERT_TRUE(bindServer(SOCK_STREAM, AF_INET, true));
-    for(int status : {200, 204, 299, 301, 404, 503})
+    for(int status : {200, 204, 299, 300, 301, 399, 404, 503})
     {
         worker = std::jthread(&ProbeTest::serveHttp, this, status, false);
         auto result_probe = createProbe(HttpEndpoint{
@@ -294,7 +294,7 @@ TEST_F(ProbeTest, HttpStatusCodes)
         ASSERT_TRUE(result_probe) << result_probe.error().msg();
         auto result = (*result_probe)->probe();
         ASSERT_TRUE(result) << result.error().msg();
-        EXPECT_EQ(result->status, status >= 200 && status < 300
+        EXPECT_EQ(result->status, status >= 200 && status < 400
             ? ProbeStatus::GOOD : ProbeStatus::BAD) << status;
         worker.join();
     }