diff --git a/A_Primer_on_Deep_Learning_in_Genomics_Public.ipynb b/A_Primer_on_Deep_Learning_in_Genomics_Public.ipynb
index 87c462a..d21fe55 100644
--- a/A_Primer_on_Deep_Learning_in_Genomics_Public.ipynb
+++ b/A_Primer_on_Deep_Learning_in_Genomics_Public.ipynb
@@ -290,10 +290,17 @@
         "one_hot_encoder = OneHotEncoder(categories='auto')   \n",
         "input_features = []\n",
         "\n",
+        "# Fit encoders first before applying transforms  \n",
+        "alphabet = list(set(letter for seq in sequences for letter in seq))  \n",
+        "integer_encoder.fit(alphabet)  \n",
+        "\n",
+        "alphabet_encoded = integer_encoder.transform(integer_encoder.classes_)  \n",
+        "one_hot_encoder.fit(np.array(alphabet_encoded).reshape(-1,1))  \n",
+        "\n",
         "for sequence in sequences:\n",
-        "  integer_encoded = integer_encoder.fit_transform(list(sequence))\n",
+        "  integer_encoded = integer_encoder.transform(list(sequence))\n",
         "  integer_encoded = np.array(integer_encoded).reshape(-1, 1)\n",
-        "  one_hot_encoded = one_hot_encoder.fit_transform(integer_encoded)\n",
+        "  one_hot_encoded = one_hot_encoder.transform(integer_encoded)\n",
         "  input_features.append(one_hot_encoded.toarray())\n",
         "\n",
         "np.set_printoptions(threshold=40)\n",
@@ -849,4 +856,4 @@
       ]
     }
   ]
-}
\ No newline at end of file
+}