diff --git a/.changeset/full-rooms-listen.md b/.changeset/full-rooms-listen.md
new file mode 100644
index 00000000..3c9481bf
--- /dev/null
+++ b/.changeset/full-rooms-listen.md
@@ -0,0 +1,5 @@
+---
+'@relayprotocol/relay-sdk': patch
+---
+
+Improve fast fills error handling
diff --git a/demo/pages/api/fast-fill.ts b/demo/pages/api/fast-fill.ts
index 1d7f1ad1..be81f1ab 100644
--- a/demo/pages/api/fast-fill.ts
+++ b/demo/pages/api/fast-fill.ts
@@ -63,18 +63,20 @@ export default async function handler(
 
       return res.status(200).json(fastFillData)
     } catch (error: any) {
-      // Handle APIError from the SDK
       if (error.statusCode) {
-        return res.status(error.statusCode).json({
-          error: error.message || 'Fast fill failed'
-        })
+        return res.status(400).json({
+          message: error.message || 'Fast fill failed',
+          code: error?.rawError?.code ?? 'UNKNOWN_ERROR'
+        } as any)
+      } else {
+        throw error
       }
-      throw error
     }
   } catch (error: any) {
     console.error('Fast fill proxy error:', error)
     return res.status(500).json({
-      error: error?.message || 'Internal server error'
-    })
+      error: error?.message || 'Internal server error',
+      code: 'UNKNOWN_ERROR'
+    } as any)
   }
 }
diff --git a/packages/sdk/src/actions/fastFill.ts b/packages/sdk/src/actions/fastFill.ts
index 79ee2f64..2d38208c 100644
--- a/packages/sdk/src/actions/fastFill.ts
+++ b/packages/sdk/src/actions/fastFill.ts
@@ -36,14 +36,14 @@ export async function fastFill(
     data: parameters,
     headers: getApiKeyHeader(client)
   }
-
-  const res = await axios.request(request)
-  if (res.status !== 200) {
+  try {
+    const res = await axios.request(request)
+    return res.data
+  } catch (error: any) {
     throw new APIError(
-      res?.data?.error || res?.data?.message,
-      res.status,
-      res.data
+      error?.message || 'Fast fill failed',
+      error?.statusCode || 500,
+      error
     )
   }
-  return res.data
 }
diff --git a/packages/sdk/src/utils/axios.ts b/packages/sdk/src/utils/axios.ts
index 791d4465..dea99ec8 100644
--- a/packages/sdk/src/utils/axios.ts
+++ b/packages/sdk/src/utils/axios.ts
@@ -17,7 +17,7 @@ axios.interceptors.response.use(
   (error) => {
     return Promise.reject(
       new APIError(
-        error.response?.data?.message,
+        error.response?.data?.message || error.response?.data?.error,
         error.response?.data?.statusCode || 500,
         {
           ...error.response?.data,