diff --git a/book/Q2/6_boltzmann.ipynb b/book/Q2/6_boltzmann.ipynb
index 0976b92..6b8e61f 100644
--- a/book/Q2/6_boltzmann.ipynb
+++ b/book/Q2/6_boltzmann.ipynb
@@ -292,8 +292,8 @@
     "        E_y[i] += p.m * p.v[1]**2 / 2\n",
     "\n",
     "plt.figure()\n",
-    "plt.xlabel('Energy')\n",
-    "plt.ylabel('time')\n",
+    "plt.xlabel('time')\n",
+    "plt.ylabel('Energy')\n",
     "\n",
     "\n",
     "plt.plot(times, E_x, '-r', label=\"x\")\n",