diff --git a/src/media-understanding/image-input-normalize.ts b/src/media-understanding/image-input-normalize.ts
index 956aaf384b1..45c2046afd6 100644
--- a/src/media-understanding/image-input-normalize.ts
+++ b/src/media-understanding/image-input-normalize.ts
@@ -1,11 +1,11 @@
-import { extractImageContentFromSource } from "../media/input-files.js";
+import { extractImageContentFromSource, normalizeMimeType } from "../media/input-files.js";
 import { DEFAULT_MAX_BYTES } from "./defaults.constants.js";
 
 const HEIC_MIME_RE = /^image\/hei[cf]$/i;
 const HEIC_EXT_RE = /\.(heic|heif)$/i;
 
 function isHeicInput(params: { mime?: string; fileName?: string }): boolean {
-  const mime = params.mime?.trim();
+  const mime = normalizeMimeType(params.mime);
   if (mime && HEIC_MIME_RE.test(mime)) {
     return true;
   }
@@ -22,7 +22,7 @@ export async function normalizeImageDescriptionInput(params: {
   if (!isHeicInput(params)) {
     return { buffer: params.buffer, mime: params.mime };
   }
-  const sourceMime = params.mime?.trim() || "image/heic";
+  const sourceMime = normalizeMimeType(params.mime) ?? "image/heic";
   const image = await extractImageContentFromSource(
     {
       type: "base64",
diff --git a/src/media-understanding/runtime.test.ts b/src/media-understanding/runtime.test.ts
index e8d274531ed..fe84e683542 100644
--- a/src/media-understanding/runtime.test.ts
+++ b/src/media-understanding/runtime.test.ts
@@ -476,8 +476,8 @@ describe("media-understanding runtime", () => {
     mocks.readLocalFileSafely.mockResolvedValue({ buffer: Buffer.from("heic-source") });
 
     await describeImageFileWithModel({
-      filePath: "/tmp/sample.heic",
-      mime: "image/heic",
+      filePath: "/tmp/sample.bin",
+      mime: "image/heic; charset=binary",
       provider: "zai",
       model: "glm-4.6v",
       prompt: "Describe it",
@@ -489,7 +489,7 @@ describe("media-understanding runtime", () => {
     expect(mocks.describeImageWithModel).toHaveBeenCalledWith(
       expect.objectContaining({
         buffer: Buffer.from("jpeg-normalized"),
-        fileName: "sample.heic",
+        fileName: "sample.bin",
         mime: "image/jpeg",
       }),
     );