diff --git a/ufl/algorithms/analysis.py b/ufl/algorithms/analysis.py
index 0df278ef2..71cbb33aa 100644
--- a/ufl/algorithms/analysis.py
+++ b/ufl/algorithms/analysis.py
@@ -91,8 +91,10 @@ def extract_type(a, ufl_types):
             # Extracting BaseArguments of an object of which a Coargument is an argument,
             # then we just return the dual argument of the Coargument and not its primal argument.
             if isinstance(ai, Coargument):
-                ufl_types = tuple(Coargument if t is BaseArgument else t for t in ufl_types)
-            base_form_objects += tuple(extract_type(ai, ufl_types))
+                new_types = tuple(Coargument if t is BaseArgument else t for t in ufl_types)
+                base_form_objects += tuple(extract_type(ai, new_types))
+            else:
+                base_form_objects += tuple(extract_type(ai, ufl_types))
         # Look for BaseArguments in BaseFormOperator's argument slots only since that's where they are by definition.
         # Don't look into operands, which is convenient for external operator composition, e.g. N1(N2; v*)
         # where N2 is seen as an operator and not a form.