diff --git a/notebooks/03.1-Classification-SVMs.ipynb b/notebooks/03.1-Classification-SVMs.ipynb
index 2c37405..2d40de5 100644
--- a/notebooks/03.1-Classification-SVMs.ipynb
+++ b/notebooks/03.1-Classification-SVMs.ipynb
@@ -228,7 +228,7 @@
       "    P = np.zeros_like(X)\n",
       "    for i, xi in enumerate(x):\n",
       "        for j, yj in enumerate(y):\n",
-      "            P[i, j] = clf.decision_function([xi, yj])\n",
+      "            P[i, j] = clf.decision_function([[xi, yj]])\n",
       "    # plot the margins\n",
       "    ax.contour(X, Y, P, colors='k',\n",
       "               levels=[-1, 0, 1], alpha=0.5,\n",
@@ -483,4 +483,4 @@
    "metadata": {}
   }
  ]
-}
\ No newline at end of file
+}