diff --git a/ufl/split_functions.py b/ufl/split_functions.py
index 71fa3dcd8..18129698e 100644
--- a/ufl/split_functions.py
+++ b/ufl/split_functions.py
@@ -50,7 +50,7 @@ def split(v):
 
     # Special case: simple element, just return function in a tuple
     element = v.ufl_element()
-    if element.num_sub_elements == 0:
+    if element.num_sub_elements() == 0:
         assert end is None
         return (v,)