diff --git a/pykat/finesse.py b/pykat/finesse.py
index 508a57807b80d99ef1effc54c72c711e893a3a67..2126d1429fc86dac09cef1e7c41978964c9c4597 100644
--- a/pykat/finesse.py
+++ b/pykat/finesse.py
@@ -344,11 +344,11 @@ class kat(object):
             
             if len(values)>0 and values[0] == 'const':
                 
-                if len(values) == 3:
+                if len(values) >= 3:
                     if values[1] in constants:
                         raise pkex.BasePyKatException('const command with the name "{0}" already used'.format(values[1]))
                     else:
-                        constants[str(values[1])] = Constant(values[1], SIfloat(values[2]), [])
+                        constants[str(values[1])] = Constant(values[1], values[2], [])
                 else:
                     raise pkex.BasePyKatException('const command "{0}" was not the correct format'.format(line))