diff --git a/firedrake/function.py b/firedrake/function.py
index 0eed4a5138..100c02be87 100644
--- a/firedrake/function.py
+++ b/firedrake/function.py
@@ -327,7 +327,7 @@ def split(self):
 
     @utils.cached_property
     def _components(self):
-        if self.function_space().value_size == 1:
+        if self.function_space().block_size == 1:
             return (self, )
         else:
             return tuple(type(self)(self.function_space().sub(i), self.topological.sub(i))