diff --git a/src/qibo/gates/abstract.py b/src/qibo/gates/abstract.py
index 1328f9edcc..6405b10dc3 100644
--- a/src/qibo/gates/abstract.py
+++ b/src/qibo/gates/abstract.py
@@ -204,8 +204,8 @@ def _find_repeated(qubits: Sequence[int]) -> int:
     def _check_control_target_overlap(self):
         """Checks that there are no qubits that are both target and
         controls."""
-        control_target = self._target_qubits + self._control_qubits
-        common = len(set(control_target)) != len(control_target)
+        control_and_target =  self._control_qubits + self._target_qubits
+        common = len(set(control_and_target)) != len(control_and_target)
         if common:
             raise_error(
                 ValueError,