diff --git a/Control/DataModelTest/DataModelTestDataCommon/scripts/dmtest_condwriter.py b/Control/DataModelTest/DataModelTestDataCommon/scripts/dmtest_condwriter.py
index 33bf30337ceedbf6c956ae46d3c97e36cfa0beda..c3bace485971def147dbc0c9dfabb60920d001c4 100755
--- a/Control/DataModelTest/DataModelTestDataCommon/scripts/dmtest_condwriter.py
+++ b/Control/DataModelTest/DataModelTestDataCommon/scripts/dmtest_condwriter.py
@@ -8,7 +8,8 @@
 
 from __future__ import print_function
 
-import sys
+import sys,os
+os.environ['CLING_STANDARD_PCH'] = 'none' #See bug ROOT-10789
 from PyCool import cool
 from CoolConvUtilities import AtlCoolLib, AtlCoolTool
 
diff --git a/DataQuality/DQUtils/tests/test_coracool.py b/DataQuality/DQUtils/tests/test_coracool.py
index de8cc0dc4f7f29a0093470bd644dd1eb47ca7f00..be9fb598efc53927656d3bbae3c3de3d3135f920 100755
--- a/DataQuality/DQUtils/tests/test_coracool.py
+++ b/DataQuality/DQUtils/tests/test_coracool.py
@@ -12,6 +12,8 @@ from quick_retrieve import browse_coracool
 
 from time import time
 
+from os import environ
+os.environ['CLING_STANDARD_PCH'] = 'none' #See bug ROOT-10789
 from PyCool import cool
 
 def fetch_lb_timestamps(since, until):
diff --git a/Database/IOVDbMetaDataTools/test/testFillSimParams.py b/Database/IOVDbMetaDataTools/test/testFillSimParams.py
index f879342aa970d410f961e1824b55ccc0e49a5da0..685f3cbd752d4d59aece7267bd92c863dd10e7fa 100755
--- a/Database/IOVDbMetaDataTools/test/testFillSimParams.py
+++ b/Database/IOVDbMetaDataTools/test/testFillSimParams.py
@@ -13,8 +13,9 @@ __version__ = "$Id: testFillSimParams.py,v 1.1 2008-05-03 08:45:54 schaffer Exp
 __author__  = "RD Schaffer <R.D.Schaffer@cern.ch>"
 
 
-import sys
+import sys,os
 import string
+os.environ['CLING_STANDARD_PCH'] = 'none' #See bug ROOT-10789
 from PyCool import cool,coral
 from IOVDbMetaDataTools import ParameterDbFiller
 
diff --git a/MagneticField/MagFieldServices/share/test_magFieldCondAlg.py b/MagneticField/MagFieldServices/share/test_magFieldCondAlg.py
index 58bc3ca1d068c6c906187833bc3d43246ee0ccfd..534954177e78ccd37d4f53b0f6f448dd4d20b218 100644
--- a/MagneticField/MagFieldServices/share/test_magFieldCondAlg.py
+++ b/MagneticField/MagFieldServices/share/test_magFieldCondAlg.py
@@ -13,6 +13,8 @@ folder = '/EXT/DCS/MAGNETS/SENSORDATA'
 
 def createDB():
    """Create sqlite file with DCS currents"""
+   import os
+   os.environ['CLING_STANDARD_PCH'] = 'none' #See bug ROOT-10789
    from PyCool import cool
    from CoolConvUtilities import AtlCoolLib, AtlCoolTool