diff --git a/11-Extended-Kalman-Filters.ipynb b/11-Extended-Kalman-Filters.ipynb
index 59d28d2..80b1a5b 100644
--- a/11-Extended-Kalman-Filters.ipynb
+++ b/11-Extended-Kalman-Filters.ipynb
@@ -1155,7 +1155,7 @@
     "        V = array(self.V_j.evalf(subs=self.subs)).astype(float)\n",
     "\n",
     "        # covariance of motion noise in control space\n",
-    "        M = array([[self.std_vel*u[0]**2, 0], \n",
+    "        M = array([[self.std_vel**2, 0], \n",
     "                   [0, self.std_steer**2]])\n",
     "\n",
     "        self.P = F @ self.P @ F.T + V @ M @ V.T\n",