diff --git a/CH01/CH01_SEC04_1_Linear.ipynb b/CH01/CH01_SEC04_1_Linear.ipynb
index 26e01c5..9ff7d39 100644
--- a/CH01/CH01_SEC04_1_Linear.ipynb
+++ b/CH01/CH01_SEC04_1_Linear.ipynb
@@ -30,7 +30,7 @@
     "b = x*a + np.random.randn(*a.shape) # Add noise\n",
     "\n",
     "plt.plot(a, x*a, color='k', linewidth=2, label='True line') # True relationship\n",
-    "plt.plot(a, b, 'x', color='r', MarkerSize = 10, label='Noisy data') # Noisy measurements\n",
+    "plt.plot(a, b, 'x', color='r', markersize = 10, label='Noisy data') # Noisy measurements\n",
     "\n",
     "U, S, VT = np.linalg.svd(a,full_matrices=False)\n",
     "xtilde = VT.T @ np.linalg.inv(np.diag(S)) @ U.T @ b # Least-square fit\n",