diff --git a/yli/utils.py b/yli/utils.py
index 6986dfa..be6375f 100644
--- a/yli/utils.py
+++ b/yli/utils.py
@@ -1,5 +1,5 @@
 #   scipy-yli: Helpful SciPy utilities and recipes
-#   Copyright © 2022  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2022–2025  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -362,14 +362,10 @@ def cols_for_formula(formula, df):
 			name = factor.name()
 			if name.startswith('C('):
 				# Contrasts expression
-				# Get the corresponding factor_info
-				factor_info = formula_get_factor_info(formula, df, name)
-				
-				# Evaluate the factor
-				categorical_box = factor_info.factor.eval(factor_info.state, df)
-				
-				# Get the column name
-				name = categorical_box.data.name
+				if ',' in name:
+					name = name[2:name.index(',')]
+				else:
+					name = name[2:name.index(')')]
 			
 			cols.add(name)