diff --git a/toolchain/mfc/case_validator.py b/toolchain/mfc/case_validator.py
index 1099b51328..419920feec 100644
--- a/toolchain/mfc/case_validator.py
+++ b/toolchain/mfc/case_validator.py
@@ -1550,7 +1550,7 @@ def check_chemistry(self):
                 tw_out = self.get(f"bc_{dir}%Twall_out")
                 self.prohibit(tw_out is None, f"Isothermal Out (bc_{dir}%isothermal_out) requires a wall temperature to be set (e.g., bc_{dir}%Twall_out).")
                 if tw_out is not None and self._is_numeric(tw_out):
-                    self.prohibit(tw_out <= 0.0, f"Wall temperature bc_{dir}%Tw_out must be strictly positive for thermodynamics (got {tw_out}).")
+                    self.prohibit(tw_out <= 0.0, f"Wall temperature bc_{dir}%Twall_out must be strictly positive for thermodynamics (got {tw_out}).")
 
     def check_misc_pre_process(self):
         """Checks miscellaneous pre-process constraints"""