diff --git a/04-One-Dimensional-Kalman-Filters.ipynb b/04-One-Dimensional-Kalman-Filters.ipynb
index 3acf016e..7271ae9f 100644
--- a/04-One-Dimensional-Kalman-Filters.ipynb
+++ b/04-One-Dimensional-Kalman-Filters.ipynb
@@ -617,7 +617,7 @@
     "    plt.plot(xs, ys, label='$\\mathcal{N}$' + f'$({g1.mean},{g1.var})$')\n",
     "\n",
     "    ys = [stats.gaussian(x, g2.mean, g2.var) for x in xs]\n",
-    "    plt.plot(xs, ys, label='$\\mathcal{N}$' + '$({g2.mean},{ge.var})$')\n",
+    "    plt.plot(xs, ys, label='$\\mathcal{N}$' + f'$({g2.mean},{g2.var})$')\n",
     "\n",
     "    ys = [stats.gaussian(x, product.mean, product.var) for x in xs]\n",
     "    plt.plot(xs, ys, label='product', ls='--')\n",