diff --git a/modules/Variables.py b/modules/Variables.py
index dd3f7f6..bfa406d 100644
--- a/modules/Variables.py
+++ b/modules/Variables.py
@@ -49,19 +49,19 @@ class Variables:
         self.trace = trace
 
     def get(self, name):
-        assert name in self.variables, "la variable {name} n'éxiste pas"
+        assert name in self.variables, f"la variable {name} n'éxiste pas"
         if self.trace:
             print(f"{trace_format}accède {name}{reset_format}", file=sys.stderr)
         return self.variables[name].value
 
     def declare(self, typ, name, value=None):
-        assert name not in self.variables, "la variable {name} existe déjà"
+        assert name not in self.variables, f"la variable {name} existe déjà"
         self.variables[name] = self.Variable(typ, value)
         if self.trace:
             print(f"{trace_format}déclare {name} = {value}{reset_format}", file=sys.stderr)
 
     def assign(self, name, value):
-        assert name in self.variables, "la variable n'éxiste pas"
+        assert name in self.variables, f"la variable n'éxiste pas"
         self.variables[name].set(value)
         if self.trace:
             print(f"{trace_format}modifie {name} = {value}{reset_format}", file=sys.stderr)