diff --git a/smop/backend.py b/smop/backend.py
index 7eabf95a..25c4883d 100644
--- a/smop/backend.py
+++ b/smop/backend.py
@@ -223,10 +223,10 @@ def _backend(self,level=0):
 
     s = """
 @function
-def {0}({1}{2}nargin=-1):
+def {0}({1}):
+    nargin = sys._getframe(1).f_locals["nargin"]
 """.format(self.ident._backend(),
-           self.args._backend(),
-           "," if self.args else "")
+           self.args._backend())
            
     return s
 
diff --git a/smop/core.py b/smop/core.py
index baf2eeaa..532cbfc1 100644
--- a/smop/core.py
+++ b/smop/core.py
@@ -709,9 +709,9 @@ def print_usage():
     raise Exception
 
 def function(f):
-    def helper(*args,**kwargs):
-        kwargs["nargin"]=len(args)
-        return f(*args,**kwargs)
+    def helper(*args):
+        nargin=len(args)
+        return f(*args)
     return helper
 
 def error(s):