diff --git a/src/Solver/Mage.py b/src/Solver/Mage.py
index 57225882..4330736e 100644
--- a/src/Solver/Mage.py
+++ b/src/Solver/Mage.py
@@ -541,7 +541,7 @@ class Mage8(Mage):
                 if name in ["command_line_arguments"]:
                     continue
 
-                if name is "mage_compute_reach_volume_balance":
+                if name == "mage_compute_reach_volume_balance":
                     value = "O" if value == "y" else "N"
 
                 f.write(f"{name} {value}\n")