diff --git a/src/lib/client.spec.ts b/src/lib/client.spec.ts
index 7103281..1f9414c 100644
--- a/src/lib/client.spec.ts
+++ b/src/lib/client.spec.ts
@@ -259,4 +259,15 @@ describe('deliverParcel', () => {
     const expectedError = new PoHTTPError(axiosError, 'Failed to deliver parcel');
     await expectPromiseToReject(deliverParcel(url, body), expectedError);
   });
+
+  test('HTTP 4XX errors should mention the reason if available', async () => {
+    // @ts-ignore
+    stubAxiosPost.mockReset();
+    const reason = 'Denied';
+    stubAxiosPost.mockRejectedValueOnce({ response: { data: { message: reason }, status: 400 } });
+
+    await expect(deliverParcel(url, body)).rejects.toEqual(
+      new PoHTTPError(`Failed to deliver parcel: ${reason}`),
+    );
+  });
 });
diff --git a/src/lib/client.ts b/src/lib/client.ts
index d91c8b6..c55cfda 100644
--- a/src/lib/client.ts
+++ b/src/lib/client.ts
@@ -66,14 +66,17 @@ async function postRequest(
     });
   } catch (error) {
     const responseStatus = error.response?.status;
+    const reason = error.response?.data?.message;
     if (responseStatus && responseStatus === 403) {
-      const reason = error.response?.data?.message;
       throw new PoHTTPInvalidParcelError(
         reason ? `Server refused to accept parcel: ${reason}` : 'Server refused to accept parcel',
       );
     }
     if (!responseStatus || responseStatus < 300 || 400 <= responseStatus) {
-      throw new PoHTTPError(error, 'Failed to deliver parcel');
+      throw new PoHTTPError(
+        error,
+        reason ? `Failed to deliver parcel: ${reason}` : 'Failed to deliver parcel',
+      );
     }
     response = error.response;
   }