diff --git a/08_unsupervised_learning.ipynb b/08_unsupervised_learning.ipynb
index bd18d4b..de3406e 100644
--- a/08_unsupervised_learning.ipynb
+++ b/08_unsupervised_learning.ipynb
@@ -504,9 +504,13 @@
     "ax.set_ylim(axes[2:4])\n",
     "ax.set_zlim(axes[4:6])\n",
     "\n",
-    "# Workaround for https://github.com/matplotlib/matplotlib/issues/12239\n",
-    "for spine in ax.spines.values():\n",
-    "    spine.set_visible(False)\n",
+    "# Note: If you are using Matplotlib 3.0.0, it has a bug and does not\n",
+    "# display 3D graphs properly.\n",
+    "# See https://github.com/matplotlib/matplotlib/issues/12239\n",
+    "# You should upgrade to a later version. If you cannot, then you can\n",
+    "# use the following workaround before displaying each 3D graph:\n",
+    "# for spine in ax.spines.values():\n",
+    "#     spine.set_visible(False)\n",
     "\n",
     "save_fig(\"dataset_3d_plot\")\n",
     "plt.show()"
@@ -571,10 +575,6 @@
     "ax.set_ylim(axes[2:4])\n",
     "ax.set_zlim(axes[4:6])\n",
     "\n",
-    "# Workaround for https://github.com/matplotlib/matplotlib/issues/12239\n",
-    "for spine in ax.spines.values():\n",
-    "    spine.set_visible(False)\n",
-    "\n",
     "save_fig(\"swiss_roll_plot\")\n",
     "plt.show()"
    ]
@@ -635,10 +635,6 @@
     "ax.set_ylim(axes[2:4])\n",
     "ax.set_zlim(axes[4:6])\n",
     "\n",
-    "# Workaround for https://github.com/matplotlib/matplotlib/issues/12239\n",
-    "for spine in ax.spines.values():\n",
-    "    spine.set_visible(False)\n",
-    "\n",
     "save_fig(\"manifold_decision_boundary_plot1\")\n",
     "plt.show()\n",
     "\n",
@@ -671,10 +667,6 @@
     "ax.set_ylim(axes[2:4])\n",
     "ax.set_zlim(axes[4:6])\n",
     "\n",
-    "# Workaround for https://github.com/matplotlib/matplotlib/issues/12239\n",
-    "for spine in ax.spines.values():\n",
-    "    spine.set_visible(False)\n",
-    "\n",
     "save_fig(\"manifold_decision_boundary_plot3\")\n",
     "plt.show()\n",
     "\n",
@@ -1265,10 +1257,6 @@
     "ax.set_yticklabels([])\n",
     "ax.set_zticklabels([])\n",
     "\n",
-    "# Workaround for https://github.com/matplotlib/matplotlib/issues/12239\n",
-    "for spine in ax.spines.values():\n",
-    "    spine.set_visible(False)\n",
-    "\n",
     "save_fig(\"preimage_plot\", tight_layout=False)\n",
     "plt.show()"
    ]