diff --git a/common/lib/chem/chem/chemcalc.py b/common/lib/chem/chem/chemcalc.py
index 27ce78b3f7..119b558fe4 100644
--- a/common/lib/chem/chem/chemcalc.py
+++ b/common/lib/chem/chem/chemcalc.py
@@ -340,11 +340,10 @@ def divide_chemical_expression(s1, s2, ignore_state=False):
             return False
 
     if any(
-        map(
-            lambda x, y: x / y - treedic['1 factors'][0] / treedic['2 factors'][0],
-            treedic['1 factors'],
-            treedic['2 factors'],
-        )
+        [
+            x / y - treedic['1 factors'][0] / treedic['2 factors'][0]
+            for (x, y) in zip(treedic['1 factors'], treedic['2 factors'])
+        ]
     ):
         # factors are not proportional
         return False