diff --git a/cylc/flow/task_pool.py b/cylc/flow/task_pool.py
index 19db5f07def..e868f653436 100644
--- a/cylc/flow/task_pool.py
+++ b/cylc/flow/task_pool.py
@@ -1704,12 +1704,12 @@ def _standardise_prereqs(
                 # The CP from --pre is invalid:
                 LOG.warning(f'Invalid pre cycle point set:\n    {exc.args[0]}')
             else:
-            _prereqs[
-                pre.duplicate(
-                    task_sel=msg,
-                    cycle=standardise_point_string(pre['cycle'])
-                )
-            ] = prereq
+                _prereqs[
+                    pre.duplicate(
+                        task_sel=msg,
+                        cycle=standardise_point_string(pre['cycle'])
+                    )
+                ] = prereq
         return _prereqs
 
     def _standardise_outputs(