diff --git a/ipython/ButterworthBandpass.ipynb b/ipython/ButterworthBandpass.ipynb
index 4798e31..4d41916 100644
--- a/ipython/ButterworthBandpass.ipynb
+++ b/ipython/ButterworthBandpass.ipynb
@@ -69,7 +69,7 @@
       "\n",
       "    # Filter a noisy signal.\n",
       "    T = 0.05\n",
-      "    nsamples = T * fs\n",
+      "    nsamples = int(T * fs)\n",
       "    t = np.linspace(0, T, nsamples, endpoint=False)\n",
       "    a = 0.02\n",
       "    f0 = 600.0\n",
@@ -120,4 +120,4 @@
    "metadata": {}
   }
  ]
-}
\ No newline at end of file
+}