diff --git a/0_Introduction.ipynb b/0_Introduction.ipynb
index a8139b8bc..e2730a35e 100644
--- a/0_Introduction.ipynb
+++ b/0_Introduction.ipynb
@@ -170,7 +170,7 @@
     "    tails = N - heads\n",
     "    \n",
     "    # Update our prior belief in closed form (this is possible because we use a conjugate prior).\n",
-    "    updated_belief = Beta(prior_belief.α + heads, prior_belief.β + tails)\n",
+    "    updated_belief = Beta(prior_belief.α + tails, prior_belief.β + heads)\n",
     "\n",
     "    # Plotting\n",
     "    plot(updated_belief, \n",