diff --git a/packages/sie_ts_sdk/src/images.ts b/packages/sie_ts_sdk/src/images.ts
index 1e94817f7..9f9a2f6e7 100644
--- a/packages/sie_ts_sdk/src/images.ts
+++ b/packages/sie_ts_sdk/src/images.ts
@@ -79,8 +79,12 @@ export async function toImageBytes(input: ImageInput): Promise<Uint8Array> {
 
   // Base64 string or data URL
   if (typeof input === "string") {
-    // Check if it's a data URL
-    const dataUrlMatch = input.match(/^data:[^;]+;base64,(.+)$/);
+    // Check if it's a base64 data URL. Per RFC 2397 the media type may carry
+    // parameters (e.g. ";charset=utf-8") or be omitted entirely, so match
+    // everything up to the ";base64," marker rather than a single ";"-free
+    // segment — otherwise such URLs fall through and the whole data URL is
+    // handed to the base64 decoder (corrupting the bytes or throwing).
+    const dataUrlMatch = input.match(/^data:[^,]*;base64,(.+)$/);
     if (dataUrlMatch?.[1]) {
       return base64ToBytes(dataUrlMatch[1]);
     }
diff --git a/packages/sie_ts_sdk/tests/images.test.ts b/packages/sie_ts_sdk/tests/images.test.ts
index 769fe3796..d560b2472 100644
--- a/packages/sie_ts_sdk/tests/images.test.ts
+++ b/packages/sie_ts_sdk/tests/images.test.ts
@@ -51,6 +51,25 @@ describe("toImageBytes", () => {
     expect(new TextDecoder().decode(result)).toBe("test");
   });
 
+  it("decodes a data URL whose media type carries a parameter", async () => {
+    // Valid per RFC 2397: the media type may be followed by ";param=value"
+    // (e.g. charset) before ";base64,". "Hello" base64-encoded.
+    const dataUrl = "data:image/svg+xml;charset=utf-8;base64,SGVsbG8=";
+    const result = await toImageBytes(dataUrl);
+
+    expect(result).toBeInstanceOf(Uint8Array);
+    expect(new TextDecoder().decode(result)).toBe("Hello");
+  });
+
+  it("decodes a data URL with an omitted media type", async () => {
+    // RFC 2397 permits an empty media type (defaults to text/plain).
+    const dataUrl = "data:;base64,SGVsbG8=";
+    const result = await toImageBytes(dataUrl);
+
+    expect(result).toBeInstanceOf(Uint8Array);
+    expect(new TextDecoder().decode(result)).toBe("Hello");
+  });
+
   it("throws for unsupported input type", async () => {
     await expect(toImageBytes(123 as unknown as Uint8Array)).rejects.toThrow(
       "Unsupported image input type",