diff --git a/docs/en/030_Supported_Protocols/005_Miniflux.md b/docs/en/030_Supported_Protocols/005_Miniflux.md
index 0d5792e..84e7d28 100644
--- a/docs/en/030_Supported_Protocols/005_Miniflux.md
+++ b/docs/en/030_Supported_Protocols/005_Miniflux.md
@@ -29,6 +29,7 @@ Miniflux version 2.0.26 is emulated, though not all features are implemented
 # Differences
 
 - Various error messages differ due to significant implementation differences
+- `PUT` requests which return a body respond with `200 OK` rather than `201 Created`
 - Only the URL should be considered reliable in feed discovery results
 - The "All" category is treated specially (see below for details)
 - Category names consisting only of whitespace are rejected along with the empty string
diff --git a/lib/REST/Miniflux/V1.php b/lib/REST/Miniflux/V1.php
index fd6baa9..d84a7e9 100644
--- a/lib/REST/Miniflux/V1.php
+++ b/lib/REST/Miniflux/V1.php
@@ -331,10 +331,12 @@ class V1 extends \JKingWeb\Arsse\REST\AbstractHandler {
     }
 
     protected function updateCategory(array $path, array $query, array $data): ResponseInterface {
+        // category IDs in Miniflux are always greater than 1; we have folder 0, so we decrement category IDs by 1 to get the folder ID
         $folder = $path[1] - 1;
         $title = $data['title'] ?? "";
         try {
             if ($folder === 0) {
+                // folder 0 doesn't actually exist in the database, so its name is kept as user metadata
                 if (!strlen(trim($title))) {
                     throw new ExceptionInput("whitespace");
                 }
@@ -345,7 +347,7 @@ class V1 extends \JKingWeb\Arsse\REST\AbstractHandler {
         } catch (ExceptionInput $e) {
             if ($e->getCode() === 10236) {
                 return new ErrorResponse(["DuplicateCategory", 'title' => $title], 500);
-            } elseif ($e->getCode === 10239) {
+            } elseif ($e->getCode() === 10239) {
                 return new ErrorResponse("404", 404);
             } else {
                 return new ErrorResponse(["InvalidCategory", 'title' => $title], 500);
diff --git a/tests/cases/REST/Miniflux/TestV1.php b/tests/cases/REST/Miniflux/TestV1.php
index 0259948..f9bb423 100644
--- a/tests/cases/REST/Miniflux/TestV1.php
+++ b/tests/cases/REST/Miniflux/TestV1.php
@@ -283,4 +283,44 @@ class TestV1 extends \JKingWeb\Arsse\Test\AbstractTest {
             [false,       new ErrorResponse(["InvalidInputType", 'field' => "title", 'actual' => "boolean", 'expected' => "string"], 400)],
         ];
     }
+
+    /** @dataProvider provideCategoryUpdates */
+    public function testRenameACategory(int $id, $title, ResponseInterface $exp): void {
+        Arsse::$user->method("propertiesSet")->willReturn(['root_folder_name' => $title]);
+        if (!in_array($id, [1,2])) {
+            \Phake::when(Arsse::$db)->folderPropertiesSet->thenThrow(new ExceptionInput("subjectMissing"));
+        } elseif (!strlen((string) $title)) {
+            \Phake::when(Arsse::$db)->folderPropertiesSet->thenThrow(new ExceptionInput("missing"));
+        } elseif (!strlen(trim((string) $title))) {
+            \Phake::when(Arsse::$db)->folderPropertiesSet->thenThrow(new ExceptionInput("whitespace"));
+        } elseif ($title === "Duplicate") {
+            \Phake::when(Arsse::$db)->folderPropertiesSet->thenThrow(new ExceptionInput("constraintViolation"));
+        } else {
+            \Phake::when(Arsse::$db)->folderPropertiesSet->thenReturn(true);
+        }
+        if ($id === 1) {
+            $times = (int) (is_string($title) && strlen(trim($title)));
+            Arsse::$user->expects($this->exactly($times))->method("propertiesSet")->with("john.doe@example.com", ['root_folder_name' => $title]);
+        }
+        $this->assertMessage($exp, $this->req("PUT", "/categories/$id", ['title' => $title]));
+        if ($id !== 1 && is_string($title)) {
+            \Phake::verify(Arsse::$db)->folderPropertiesSet("john.doe@example.com", $id - 1, ['name' => $title]);
+        }
+    }
+
+    public function provideCategoryUpdates(): iterable {
+        return [
+            [3, "New",       new ErrorResponse("404", 404)],
+            [2, "New",       new Response(['id' => 2, 'title' => "New", 'user_id' => 42])],
+            [2, "Duplicate", new ErrorResponse(["DuplicateCategory", 'title' => "Duplicate"], 500)],
+            [2, "",          new ErrorResponse(["InvalidCategory", 'title' => ""], 500)],
+            [2, " ",         new ErrorResponse(["InvalidCategory", 'title' => " "], 500)],
+            [2, false,       new ErrorResponse(["InvalidInputType", 'field' => "title", 'actual' => "boolean", 'expected' => "string"], 400)],
+            [1, "New",       new Response(['id' => 1, 'title' => "New", 'user_id' => 42])],
+            [1, "Duplicate", new Response(['id' => 1, 'title' => "Duplicate", 'user_id' => 42])], // This is allowed because the name of the root folder is only a duplicate in circumstances where it is used
+            [1, "",          new ErrorResponse(["InvalidCategory", 'title' => ""], 500)],
+            [1, " ",         new ErrorResponse(["InvalidCategory", 'title' => " "], 500)],
+            [1, false,       new ErrorResponse(["InvalidInputType", 'field' => "title", 'actual' => "boolean", 'expected' => "string"], 400)],
+        ];
+    }
 }