diff --git a/tasks/task_01_cross_sections/4_Doppler_broadening.ipynb b/tasks/task_01_cross_sections/4_Doppler_broadening.ipynb
index 301a3e99..34b951bf 100644
--- a/tasks/task_01_cross_sections/4_Doppler_broadening.ipynb
+++ b/tasks/task_01_cross_sections/4_Doppler_broadening.ipynb
@@ -1,6 +1,7 @@
 {
  "cells": [
   {
+   "attachments": {},
    "cell_type": "markdown",
    "metadata": {},
    "source": [
@@ -34,6 +35,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "metadata": {},
    "source": [
@@ -50,7 +52,7 @@
     "\n",
     "mt_number = REACTION_MT[\"(n,total)\"]  # looks up the MT number for the total reaction\n",
     "\n",
-    "h5_file = f\"WMP_Library/074186.h5\"  # 074186 is W186\n",
+    "h5_file = f\"/WMP_Library/074186.h5\"  # 074186 is W186\n",
     "\n",
     "isotope_multipole = openmc.data.WindowedMultipole.from_hdf5(h5_file)  # loads up the WMP cross section file\n",
     "\n",
@@ -70,6 +72,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "metadata": {},
    "source": [
@@ -77,6 +80,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "metadata": {},
    "source": [
@@ -93,7 +97,7 @@
     "\n",
     "mt_number = REACTION_MT[\"(n,total)\"]  # looks up the MT number for the total reaction\n",
     "\n",
-    "h5_file = f\"WMP_Library/026056.h5\"  # 026056 is Fe56\n",
+    "h5_file = f\"/WMP_Library/026056.h5\"  # 026056 is Fe56\n",
     "\n",
     "isotope_multipole = openmc.data.WindowedMultipole.from_hdf5(h5_file)  # loads up the WMP cross section file\n",
     "\n",
@@ -113,6 +117,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "metadata": {},
    "source": [