diff --git a/django/db/models/aggregates.py b/django/db/models/aggregates.py
index dfae09e34f9..00245b4a86d 100644
--- a/django/db/models/aggregates.py
+++ b/django/db/models/aggregates.py
@@ -27,10 +27,6 @@ class Aggregate(Func):
         c._patch_aggregate(query)  # backward-compatibility support
         return c
 
-    @property
-    def input_field(self):
-        return self.source_expressions[0]
-
     @property
     def default_alias(self):
         expressions = self.get_source_expressions()