diff --git a/elab_users/__init__.py b/elab_users/__init__.py
index de24c29..ae0af7c 100644
--- a/elab_users/__init__.py
+++ b/elab_users/__init__.py
@@ -90,7 +90,7 @@ def retire_user(
 ):
     config = get_config(svn_dir, authz)
     if username not in config.elab_users:
-        sys.exit("User {username} not found.")
+        sys.exit(f"User {username} not found.")
     user = config.elab_users[username]
     if user.group == ALUMNI:
         sys.exit(f"User '{username}' is already in group '{ALUMNI}'")
@@ -116,7 +116,7 @@ def change_password(
 ):
     config = get_config(svn_dir, authz)
     if username not in config.elab_users:
-        sys.exit("User {username} not found.")
+        sys.exit(f"User {username} not found.")
     user = config.elab_users[username]
     password = user.set_new_password(svn_dir / htpwd, handler=handler)
     print("New password for :")
@@ -127,7 +127,7 @@ def change_password(
 def show_user_info(username, svn_dir=SVN_REPOS_PATH, authz=AUTHZ_FILE_NAME):
     config = get_config(svn_dir, authz)
     if username not in config.elab_users:
-        sys.exit("User {username} not found.")
+        sys.exit(f"User {username} not found.")
 
     user = config.elab_users[username]
     print(f"User {user.name} is in group '{user.group}':")