diff --git a/CHANGELOG.md b/CHANGELOG.md
index b367e83c8..cd3709f9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ SPDX-License-Identifier: GPL-3.0-or-later
 - core: write configuration files on disk only if there are changes ([#2250](https://github.com/weechat/weechat/issues/2250))
 - core: always enable partial completion for templates in option weechat.completion.partial_completion_templates, add option weechat.completion.partial_completion_auto_expand to expand word on new completion ([#2253](https://github.com/weechat/weechat/issues/2253))
 - core: add script name in output of `/debug hooks <plugin>`
+- relay/api: return HTTP error 405 (Method Not Allowed) when the method received is not allowed
 
 ### Added
 
diff --git a/src/plugins/relay/api/relay-api-protocol.c b/src/plugins/relay/api/relay-api-protocol.c
index e2e8d56c1..167cb5520 100644
--- a/src/plugins/relay/api/relay-api-protocol.c
+++ b/src/plugins/relay/api/relay-api-protocol.c
@@ -374,7 +374,7 @@ RELAY_API_PROTOCOL_CALLBACK(options)
     relay_api_msg_send_json (
         client,
         RELAY_HTTP_204_NO_CONTENT,
-        "Access-Control-Allow-Methods: GET, POST, PUT, DELETE\r\n"
+        "Access-Control-Allow-Methods: " RELAY_API_ALLOWED_METHODS "\r\n"
         "Access-Control-Allow-Headers: origin, content-type, accept, authorization",
         NULL,  /* body_type */
         NULL);  /* json_body */
@@ -1197,7 +1197,7 @@ relay_api_protocol_recv_json (struct t_relay_client *client, const char *json)
 void
 relay_api_protocol_recv_http (struct t_relay_client *client)
 {
-    int i, num_args;
+    int i, num_args, match_method, match_resource;
     char str_error[1024];
     enum t_relay_api_protocol_rc return_code;
     struct t_relay_api_protocol_cb protocol_cb[] = {
@@ -1238,18 +1238,22 @@ relay_api_protocol_recv_http (struct t_relay_client *client)
         || !client->http_req->path_items[1]
         || (strcmp (client->http_req->path_items[0], "api") != 0))
     {
-        goto error_not_found;
+        goto resource_not_found;
     }
 
     num_args = client->http_req->num_path_items - 2;
 
     for (i = 0; protocol_cb[i].resource; i++)
     {
-        if (strcmp (protocol_cb[i].method, client->http_req->method) != 0)
-            continue;
+        match_method = (strcmp (protocol_cb[i].method, client->http_req->method) == 0);
 
-        if ((strcmp (protocol_cb[i].resource, "*") != 0)
-            && (strcmp (protocol_cb[i].resource, client->http_req->path_items[1]) != 0))
+        match_resource = ((strcmp (protocol_cb[i].resource, "*") == 0)
+                          || (strcmp (protocol_cb[i].resource, client->http_req->path_items[1]) == 0));
+
+        if (!match_method && (strcmp (protocol_cb[i].resource, "*") != 0) && match_resource)
+            goto error_method_not_allowed;
+
+        if (!match_method || !match_resource)
             continue;
 
         if (protocol_cb[i].auth_required
@@ -1331,7 +1335,18 @@ relay_api_protocol_recv_http (struct t_relay_client *client)
         }
     }
 
-    goto error_not_found;
+resource_not_found:
+    if ((strcmp (client->http_req->method, "GET") != 0)
+        && (strcmp (client->http_req->method, "POST") != 0)
+        && (strcmp (client->http_req->method, "PUT") != 0)
+        && (strcmp (client->http_req->method, "DELETE") != 0))
+    {
+        goto error_method_not_allowed;
+    }
+    else
+    {
+        goto error_not_found;
+    }
 
 error_bad_request:
     relay_api_msg_send_error_json (client, RELAY_HTTP_400_BAD_REQUEST,
@@ -1343,6 +1358,12 @@ error_not_found:
                                    NULL, RELAY_HTTP_ERROR_NOT_FOUND);
     goto error;
 
+error_method_not_allowed:
+    relay_api_msg_send_error_json (client, RELAY_HTTP_405_METHOD_NOT_ALLOWED,
+                                   "Allow: " RELAY_API_ALLOWED_METHODS,
+                                   RELAY_HTTP_ERROR_METHOD_NOT_ALLOWED);
+    goto error;
+
 error_memory:
     relay_api_msg_send_error_json (client, RELAY_HTTP_503_SERVICE_UNAVAILABLE,
                                    NULL, RELAY_HTTP_ERROR_OUT_OF_MEMORY);
diff --git a/src/plugins/relay/api/relay-api-protocol.h b/src/plugins/relay/api/relay-api-protocol.h
index cb09bb548..c1bc1216f 100644
--- a/src/plugins/relay/api/relay-api-protocol.h
+++ b/src/plugins/relay/api/relay-api-protocol.h
@@ -22,6 +22,8 @@
 #ifndef WEECHAT_PLUGIN_RELAY_API_PROTOCOL_H
 #define WEECHAT_PLUGIN_RELAY_API_PROTOCOL_H
 
+#define RELAY_API_ALLOWED_METHODS "GET, POST, PUT, DELETE"
+
 #define RELAY_API_CB(__command) &relay_api_protocol_cb_##__command
 #define RELAY_API_PROTOCOL_CALLBACK(__command)                          \
     enum t_relay_api_protocol_rc                                        \
diff --git a/src/plugins/relay/relay-http.h b/src/plugins/relay/relay-http.h
index 4c28d48b9..14d9e943f 100644
--- a/src/plugins/relay/relay-http.h
+++ b/src/plugins/relay/relay-http.h
@@ -40,6 +40,7 @@ enum t_relay_client_http_status
 #define RELAY_HTTP_401_UNAUTHORIZED           401, "Unauthorized"
 #define RELAY_HTTP_403_FORBIDDEN              403, "Forbidden"
 #define RELAY_HTTP_404_NOT_FOUND              404, "Not Found"
+#define RELAY_HTTP_405_METHOD_NOT_ALLOWED     405, "Method Not Allowed"
 #define RELAY_HTTP_500_INTERNAL_SERVER_ERROR  500, "Internal Server Error"
 #define RELAY_HTTP_503_SERVICE_UNAVAILABLE    503, "Service Unavailable"
 
@@ -53,6 +54,7 @@ enum t_relay_client_http_status
 #define RELAY_HTTP_ERROR_INVALID_ITERATIONS   "Invalid number of iterations"
 #define RELAY_HTTP_ERROR_BAD_REQUEST          "Bad request"
 #define RELAY_HTTP_ERROR_NOT_FOUND            "Resource not found"
+#define RELAY_HTTP_ERROR_METHOD_NOT_ALLOWED   "Method Not Allowed"
 #define RELAY_HTTP_ERROR_OUT_OF_MEMORY        "Out of memory"
 
 struct t_relay_http_request
diff --git a/tests/unit/plugins/relay/api/test-relay-api-protocol.cpp b/tests/unit/plugins/relay/api/test-relay-api-protocol.cpp
index afa77de01..65891b693 100644
--- a/tests/unit/plugins/relay/api/test-relay-api-protocol.cpp
+++ b/tests/unit/plugins/relay/api/test-relay-api-protocol.cpp
@@ -1052,3 +1052,44 @@ TEST(RelayApiProtocolWithClient, RecvHttpInvalidPassword)
                  "{\"error\":\"Invalid password\"}",
                  data_sent[0]);
 }
+
+/*
+ * Tests functions:
+ *   relay_api_protocol_recv_http (method not allowed)
+ */
+
+TEST(RelayApiProtocolWithClient, RecvHttpMethodNotAllowed)
+{
+    /* method not allowed (PATCH) with existing resource (/api/ping) */
+    test_client_recv_http ("PATCH /api/ping", NULL, "{\"data\": \"abcdef\"}");
+    STRCMP_EQUAL("HTTP/1.1 405 Method Not Allowed\r\n"
+                 "Allow: GET, POST, PUT, DELETE\r\n"
+                 "Access-Control-Allow-Origin: *\r\n"
+                 "Content-Type: application/json; charset=utf-8\r\n"
+                 "Content-Length: 30\r\n"
+                 "\r\n"
+                 "{\"error\":\"Method Not Allowed\"}",
+                 data_sent[0]);
+
+    /* method not allowed (PATCH) with unknown resource (/api/unknown) */
+    test_client_recv_http ("PATCH /api/unknown", NULL, "{\"data\": \"abcdef\"}");
+    STRCMP_EQUAL("HTTP/1.1 405 Method Not Allowed\r\n"
+                 "Allow: GET, POST, PUT, DELETE\r\n"
+                 "Access-Control-Allow-Origin: *\r\n"
+                 "Content-Type: application/json; charset=utf-8\r\n"
+                 "Content-Length: 30\r\n"
+                 "\r\n"
+                 "{\"error\":\"Method Not Allowed\"}",
+                 data_sent[0]);
+
+    /* method not allowed (PATCH) with unknown resource (/unknown) */
+    test_client_recv_http ("PATCH /unknown", NULL, "{\"data\": \"abcdef\"}");
+    STRCMP_EQUAL("HTTP/1.1 405 Method Not Allowed\r\n"
+                 "Allow: GET, POST, PUT, DELETE\r\n"
+                 "Access-Control-Allow-Origin: *\r\n"
+                 "Content-Type: application/json; charset=utf-8\r\n"
+                 "Content-Length: 30\r\n"
+                 "\r\n"
+                 "{\"error\":\"Method Not Allowed\"}",
+                 data_sent[0]);
+}