diff --git a/statstests/pytests/test.py b/statstests/pytests/test.py
new file mode 100644
index 0000000..bdc944e
--- /dev/null
+++ b/statstests/pytests/test.py
@@ -0,0 +1,14 @@
+import pytest
+import pandas as pd
+
+def test_replace():
+    """
+        Test to validate changes
+    """    
+    df = pd.DataFrame({'[col.1]': [1, 2], '[col.2]': [3, 4]})
+    df.columns = df.columns.str.replace('\[', '', regex=True)
+    df.columns = df.columns.str.replace('\.', '_', regex=True)
+    df.columns = df.columns.str.replace('\]', '', regex=True)
+
+    df_expected = pd.DataFrame({'col_1': [1, 2], 'col_2': [3, 4]})    
+    assert df.columns.all() == df_expected.columns.all()
diff --git a/statstests/tests.py b/statstests/tests.py
index 45dfe97..2e14e75 100644
--- a/statstests/tests.py
+++ b/statstests/tests.py
@@ -123,9 +123,9 @@ def overdisp(model, data):
                     model.model.data.orig_exog], axis=1)
 
     # adjust column names with special characters from categorical columns
-    df.columns = df.columns.str.replace('[', '', regex=True)
-    df.columns = df.columns.str.replace('.', '_', regex=True)
-    df.columns = df.columns.str.replace(']', '', regex=True)
+    df.columns = df.columns.str.replace('\[', '', regex=True)
+    df.columns = df.columns.str.replace('\.', '_', regex=True)
+    df.columns = df.columns.str.replace('\]', '', regex=True)
 
     # adjust formula with special characters from categorical columns
     formula = formula.replace("[", "")