diff --git a/interface/ri_func_dep.py b/interface/ri_func_dep.py
index d578df0..9e29f9a 100644
--- a/interface/ri_func_dep.py
+++ b/interface/ri_func_dep.py
@@ -40,9 +40,9 @@ class FileSystem(FunctionDepending):
             return False
         return True
 
-def error(self):
-    mesg="format filesystem " + self.filesystem_type
-    return {mesg:self.package}
+    def error(self):
+        mesg="format filesystem " + self.filesystem_type
+        return {mesg:self.package}
 
 class DHCP(FunctionDepending):
     def __init__(self):