diff --git a/10-Unscented-Kalman-Filter.ipynb b/10-Unscented-Kalman-Filter.ipynb
index a27518f..e5fb9c9 100644
--- a/10-Unscented-Kalman-Filter.ipynb
+++ b/10-Unscented-Kalman-Filter.ipynb
@@ -2227,7 +2227,7 @@
     "    \"\"\"\n",
     "\n",
     "    # calculate sigma points for given mean and covariance\n",
-    "    sigmas = sigma_points_fn(self.x, self.P)\n",
+    "    sigmas = sigma_points_fn(self.x, self.Pp)\n",
     "\n",
     "    for i in range(self._num_sigmas):\n",
     "        self.sigmas_f[i] = self.fx(sigmas[i], self._dt)\n",
@@ -3257,7 +3257,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.6"
+   "version": "3.7.4"
   }
  },
  "nbformat": 4,