diff --git a/plugins/Math/plugin.py b/plugins/Math/plugin.py
index 2c441ac5b..29bbf0bb1 100644
--- a/plugins/Math/plugin.py
+++ b/plugins/Math/plugin.py
@@ -109,7 +109,7 @@ class Math(callbacks.Plugin):
         return math.pow(x, 1.0/3)
     def _factorial(x):
         if x<=10000:
-            return math.factorial(x)
+            return float(math.factorial(x))
         else:
             raise Exception('factorial argument too large')
     _mathEnv['sqrt'] = _sqrt