diff --git a/PREM_density_example.ipynb b/PREM_density_example.ipynb
index cb6a826..1e8e238 100644
--- a/PREM_density_example.ipynb
+++ b/PREM_density_example.ipynb
@@ -165,8 +165,8 @@
    ],
    "source": [
     "print(\"Mass of the Earth is:\", prem.mass(prem.r_earth), \"kg\")\n",
-    "print(\"Earth's moment of inertia is: \", prem.moment_or_inertia(prem.r_earth)[0], \"kg m^2\")\n",
-    "print(\"I/MR**2:\", prem.moment_or_inertia(prem.r_earth)[1])\n",
+    "print(\"Earth's moment of inertia is: \", prem.moment_of_inertia(prem.r_earth)[0], \"kg m^2\")\n",
+    "print(\"I/MR**2:\", prem.moment_of_inertia(prem.r_earth)[1])\n",
     "\n",
     "# What does it look like?\n",
     "fig, ax = plt.subplots(figsize=(10,6))\n",
diff --git a/earth_model/earth_model.py b/earth_model/earth_model.py
index 53026de..9f6b30b 100644
--- a/earth_model/earth_model.py
+++ b/earth_model/earth_model.py
@@ -178,7 +178,7 @@ def mass(self, r, r_inner=0.0):
                     m[i] = self.mass_poly.integrate(r_inner, r[i])
         return m
 
-    def moment_or_inertia(self, r, r_inner=0.0):
+    def moment_of_inertia(self, r, r_inner=0.0):
         """
         Evaluate moment of inertia inside radius r (in km)