diff --git a/Notebooks/Chap04/4_2_Clipping_functions.ipynb b/Notebooks/Chap04/4_2_Clipping_functions.ipynb
index 87ecab2..e271244 100644
--- a/Notebooks/Chap04/4_2_Clipping_functions.ipynb
+++ b/Notebooks/Chap04/4_2_Clipping_functions.ipynb
@@ -169,7 +169,7 @@
     {
       "cell_type": "code",
       "source": [
-        "# Define parameters (note first dimension of theta and phi is padded to make indices match\n",
+        "# Define parameters (note first dimension of theta and psi is padded to make indices match\n",
         "# notation in book)\n",
         "theta = np.zeros([4,2])\n",
         "psi = np.zeros([4,4])\n",