diff --git a/calculate/lib/datavars.py b/calculate/lib/datavars.py
index ffae995..bf36bdc 100644
--- a/calculate/lib/datavars.py
+++ b/calculate/lib/datavars.py
@@ -263,15 +263,15 @@ class Variable:
         section = self.parent.iniCache[self.name]['section']
         value = self.parent.unserialize(self.type,
                                  value.encode('utf-8'))
-        try:
-            if self.mode == READONLY:
-                raise VariableError(
-                    _("Attempt to rewrite readonly variable %s")%
-                    varname)
-            else:
+        if self.mode == READONLY:
+            raise VariableError(
+                _("Attempt to rewrite readonly variable %s")%
+                self.name)
+        else:
+            try:
                 self._set(value)
-        except Exception as e:
-            return False
+            except Exception as e:
+                return False
         return True
 
     def _get(self):