diff --git a/src/tools/blog.ts b/src/tools/blog.ts
index 5429303..72b0875 100644
--- a/src/tools/blog.ts
+++ b/src/tools/blog.ts
@@ -37,7 +37,7 @@ export function registerBlogTools(server: McpServer, client: BetterNewsClient) {
             title: z.string().min(1).max(150).describe("Post title"),
             content: z.string().min(1).describe("Post body (markdown supported)"),
             excerpt: z.string().max(300).optional().describe("Short excerpt shown in listings"),
-            imageUrl: z.string().url().optional().describe("Hero image URL"),
+            imageUrl: z.string().url().nullable().optional().describe("Hero image URL"),
         },
         handleTool(async (body) => {
             const data = await client.post<unknown>("/api/blog", body);