diff --git a/src/usb/lwip/rest.c b/src/usb/lwip/rest.c
index 6f468f0..b146802 100644
--- a/src/usb/lwip/rest.c
+++ b/src/usb/lwip/rest.c
@@ -293,11 +293,21 @@ const char *rest_method_to_string(rest_http_method_t method) {
     }
 }
 
-bool rest_content_type_is_json(const char *content_type) {
+bool rest_supported_content_type(const char *content_type) {
     if (content_type == NULL) {
         return false;
     }
-    return strncasecmp(content_type, "application/json", 16) == 0;
+    const char *supported_types[] = {
+        "application/json",
+        "application/x-pem-file"
+    };
+    printf("[rest] Checking content type: %s\n", content_type);
+    for (size_t i = 0; i < sizeof(supported_types) / sizeof(supported_types[0]); i++) {
+        if (strncasecmp(content_type, supported_types[i], strlen(supported_types[i])) == 0) {
+            return true;
+        }
+    }
+    return false;
 }
 
 #ifndef _MSC_VER
diff --git a/src/usb/lwip/rest.h b/src/usb/lwip/rest.h
index e85929e..96221d6 100644
--- a/src/usb/lwip/rest.h
+++ b/src/usb/lwip/rest.h
@@ -167,7 +167,7 @@ extern int rest_execute_route_handler(const rest_request_t *request, rest_route_
 extern int rest_response_set_error(rest_response_t *response, int status_code, const char *message);
 const char *rest_status_text_from_code(uint16_t code);
 const char *rest_method_to_string(rest_http_method_t method);
-bool rest_content_type_is_json(const char *content_type);
+bool rest_supported_content_type(const char *content_type);
 
 const rest_route_t *rest_get_routes(size_t *count);
 
diff --git a/src/usb/lwip/rest_server.c b/src/usb/lwip/rest_server.c
index ac88fc4..6a5509c 100644
--- a/src/usb/lwip/rest_server.c
+++ b/src/usb/lwip/rest_server.c
@@ -754,8 +754,8 @@ void rest_handle_request(rest_conn_t *conn) {
     rest_debug_dump_payload("request-body", request->body, request->body_len);
 
     if (request->method == REST_HTTP_POST || request->method == REST_HTTP_PUT) {
-        if (!rest_content_type_is_json(request->content_type) && strncasecmp(request->content_type, "application/x-pem-file", 22) != 0) {
-            send_json_error(conn, 415, "content_type_must_be_application_json");
+        if (!rest_supported_content_type(request->content_type)) {
+            send_json_error(conn, 415, "content_type_not_supported");
             return;
         }
     }