diff --git a/server/server_matrix.go b/server/server_matrix.go
index ebc2913..7204bfa 100644
--- a/server/server_matrix.go
+++ b/server/server_matrix.go
@@ -124,7 +124,7 @@ func newRequestFromMatrixJSON(r *http.Request, baseURL string, messageLimit int)
 	}
 	pushKey := m.Notification.Devices[0].PushKey // We ignore other devices for now, see discussion in #316
 	if !strings.HasPrefix(pushKey, baseURL+"/") {
-		return nil, &errMatrix{pushKey: pushKey, err: wrapErrHTTP(errHTTPBadRequestMatrixPushkeyBaseURLMismatch, "; received pushKey: %s, configured base url: %s", pushKey, baseURL)}
+		return nil, &errMatrix{pushKey: pushKey, err: wrapErrHTTP(errHTTPBadRequestMatrixPushkeyBaseURLMismatch, "received push key: %s, configured base URL: %s", pushKey, baseURL)}
 	}
 	newRequest, err := http.NewRequest(http.MethodPost, pushKey, io.NopCloser(bytes.NewReader(body.PeekedBytes)))
 	if err != nil {
diff --git a/server/server_matrix_test.go b/server/server_matrix_test.go
index 9129d6c..b2f9b1d 100644
--- a/server/server_matrix_test.go
+++ b/server/server_matrix_test.go
@@ -56,7 +56,7 @@ func TestMatrix_NewRequestFromMatrixJSON_MismatchingPushKey(t *testing.T) {
 	_, err := newRequestFromMatrixJSON(r, baseURL, maxLength)
 	matrixErr, ok := err.(*errMatrix)
 	require.True(t, ok)
-	require.Equal(t, errHTTPBadRequestMatrixPushkeyBaseURLMismatch, matrixErr.err)
+	require.Equal(t, "invalid request: push key must be prefixed with base URL, received push key: https://ntfy.example.com/upABCDEFGHI?up=1, configured base URL: https://ntfy.sh", matrixErr.err.Error())
 	require.Equal(t, "https://ntfy.example.com/upABCDEFGHI?up=1", matrixErr.pushKey)
 }