diff --git a/src/utils/regress.py b/src/utils/regress.py
index 369ae93fb1fb64493303e56e03324a2c3c668e70..ab07cfc133a49f65ddadb13dc71f81d7f5459c03 100644
--- a/src/utils/regress.py
+++ b/src/utils/regress.py
@@ -109,7 +109,9 @@ class Plsr(Regmodel):
         params['n_components'] = int(params['n_components'])
         x0 = [self._xc, self._xt]
 
-        x1 = [eval(str(params['normalization'])+'(x0[i])') for i in range(2)]
+        x1 = []
+        x1.append(eval(str(params['normalization'])+'(x0[0])'))
+        x1.append(eval(str(params['normalization'])+'(x0[1])'))
 
         a, b, c = params['deriv'], params['polyorder'], params['window_length']
         if a > b or b > c: