diff --git a/Control/AthenaConfiguration/python/AthConfigFlags.py b/Control/AthenaConfiguration/python/AthConfigFlags.py
index 22f35aa084bd76a441b0da859f09eaf8cb02c4bd..b122a659bf9d2b211cea0e5e261e27cf4b56d23a 100644
--- a/Control/AthenaConfiguration/python/AthConfigFlags.py
+++ b/Control/AthenaConfiguration/python/AthConfigFlags.py
@@ -6,6 +6,7 @@ from enum import EnumMeta
 import importlib
 from AthenaCommon.Logging import logging
 from PyUtils.moduleExists import moduleExists
+from PyUtils.Decorators import deprecate
 
 _msg = logging.getLogger('AthConfigFlags')
 
@@ -415,6 +416,7 @@ class AthConfigFlags(object):
             raise KeyError(f"No flag with name '{name}' found" +
                            (f". Did you mean '{closestMatch[0]}'?" if closestMatch else ""))
 
+    @deprecate("Use '[...]' rather than '(...)' to access flags", print_context=True)
     def __call__(self,name):
         return self._get(name)
 
diff --git a/Control/AthenaConfiguration/python/DetectorConfigFlags.py b/Control/AthenaConfiguration/python/DetectorConfigFlags.py
index a618877372633e7311d5ba7a8dfd48a208af5770..a3cb59397fec7b6c0a7468a8386feb3966fe937f 100644
--- a/Control/AthenaConfiguration/python/DetectorConfigFlags.py
+++ b/Control/AthenaConfiguration/python/DetectorConfigFlags.py
@@ -176,7 +176,7 @@ def getEnabledDetectors(flags, geometry=False):
         # test whether each detector is on
         name = f'Detector.Geometry{d}' if geometry else f'Detector.Enable{d}'
         if flags.hasFlag(name):
-            if flags(name) is not False:
+            if flags[name] is not False:
                 values.append(d)
     return values
 
@@ -254,7 +254,7 @@ def _getDetectorFlagStatus(flags, list=None, geometry=False):
                 else:
                     values.append('--')
             else:
-                if flags(name) is not False:
+                if flags[name] is not False:
                     values.append('ON')
                 else:
                     values.append('--')
@@ -395,7 +395,7 @@ def setupDetectorsFromList(flags, detectors, toggle_geometry=False, validate_onl
         status = d in detectors
         name = f'Detector.Enable{d}'
         if flags.hasFlag(name):
-            if flags(name) != status:
+            if flags[name] != status:
                 changed = True
                 if validate_only:
                     log.warning("Flag '%s' should be %s but is set to %s", name, status, not status)
@@ -405,7 +405,7 @@ def setupDetectorsFromList(flags, detectors, toggle_geometry=False, validate_onl
         if toggle_geometry:
             name = f'Detector.Geometry{d}'
             if flags.hasFlag(name):
-                if flags(name) != status:
+                if flags[name] != status:
                     changed = True
                     if validate_only:
                         log.warning("Flag '%s' should be %s but is set to %s", name, status, not status)
diff --git a/Reconstruction/RecJobTransforms/python/RecoConfigFlags.py b/Reconstruction/RecJobTransforms/python/RecoConfigFlags.py
index e3350322ce0389290a9c5119194d8c505a84dadf..335f1663dd48c805b17a8f6c5c6517aca27c15b3 100644
--- a/Reconstruction/RecJobTransforms/python/RecoConfigFlags.py
+++ b/Reconstruction/RecJobTransforms/python/RecoConfigFlags.py
@@ -176,7 +176,7 @@ def printRecoFlags(flags):
         else:
             raise RuntimeError(f'Unknown reconstruction domain {d}')
 
-        if flags(name) is not False:
+        if flags[name] is not False:
             enabled.append('ON')
         else:
             enabled.append('--')
diff --git a/Tools/PyUtils/CMakeLists.txt b/Tools/PyUtils/CMakeLists.txt
index f8194e8681d0e99eb59dced6059e88417de84bf3..b6a0c739b96f6287ee083365712e1355d4648814 100644
--- a/Tools/PyUtils/CMakeLists.txt
+++ b/Tools/PyUtils/CMakeLists.txt
@@ -17,6 +17,7 @@ if( XAOD_STANDALONE )
                                   python/moduleExists.py
                                   python/RootUtils.py
                                   python/Helpers.py
+                                  python/Decorators.py
                                   POST_BUILD_CMD ${ATLAS_FLAKE8} )
     atlas_install_scripts( bin/meta-reader.py bin/meta-diff.py
                            POST_BUILD_CMD ${ATLAS_FLAKE8} )