diff --git a/Dueling Double DQN with PER and fixed-q targets/Dueling Deep Q Learning with Doom (+ double DQNs and Prioritized Experience Replay).ipynb b/Dueling Double DQN with PER and fixed-q targets/Dueling Deep Q Learning with Doom (+ double DQNs and Prioritized Experience Replay).ipynb
index e4001bf..aea24d2 100644
--- a/Dueling Double DQN with PER and fixed-q targets/Dueling Deep Q Learning with Doom (+ double DQNs and Prioritized Experience Replay).ipynb	
+++ b/Dueling Double DQN with PER and fixed-q targets/Dueling Deep Q Learning with Doom (+ double DQNs and Prioritized Experience Replay).ipynb	
@@ -665,8 +665,8 @@
     "        parent_index = 0\n",
     "        \n",
     "        while True: # the while loop is faster than the method in the reference code\n",
-    "            left_child_index = 2 * parent_index + 1\n",
-    "            right_child_index = left_child_index + 1\n",
+    "            right_child_index = 2 * parent_index + 1\n",
+    "            left_child_index = left_child_index + 1\n",
     "            \n",
     "            # If we reach bottom, end the search\n",
     "            if left_child_index >= len(self.tree):\n",