diff --git a/assets/typescript/Forum/Posting.ts b/assets/typescript/Forum/Posting.ts
index ac46bb27..acade6c9 100644
--- a/assets/typescript/Forum/Posting.ts
+++ b/assets/typescript/Forum/Posting.ts
@@ -157,7 +157,7 @@ function forumPostingPreview(
             callback(false, 'Failed to render preview.');
         }
     });
-    xhr.open('POST', '/forum/posting.php');
+    xhr.open('POST', urlFormat('forum-topic-new'));
     xhr.withCredentials = true;
     xhr.send(formData);
 }
diff --git a/src/tpl.php b/src/tpl.php
index 705a49bc..eceab438 100644
--- a/src/tpl.php
+++ b/src/tpl.php
@@ -47,7 +47,7 @@ function tpl_sanitise_path(string $path): string
         return $path;
     }
 
-    return str_replace('.', '/', $path) . MSZ_TPL_FILE_EXT;
+    return str_replace('.', DIRECTORY_SEPARATOR, $path) . MSZ_TPL_FILE_EXT;
 }
 
 function tpl_exists(string $path): bool