diff --git a/sconstruct b/sconstruct
index 6132a8fe360..062e7a8882e 100755
--- a/sconstruct
+++ b/sconstruct
@@ -38,6 +38,7 @@ def recursiveCopy(env,targetDir,sourceDir):
 import gettext
 gettext.install("nvda")
 sys.path.append("source")
+import comtypesMonkeyPatches
 import versionInfo
 del sys.path[-1]
 
diff --git a/source/comInterfaces_sconscript b/source/comInterfaces_sconscript
index fe29e33ac76..ab05f52d13d 100755
--- a/source/comInterfaces_sconscript
+++ b/source/comInterfaces_sconscript
@@ -31,11 +31,9 @@ interfaceBuilder=env.Builder(
 )
 env['BUILDERS']['comtypesInterface']=interfaceBuilder
 
-	#Bit of a dance to force comtypes generated interfaces in to our directory
+# Force comtypes generated interfaces in to our directory
 import comtypes.client
 comtypes.client.gen_dir=Dir('comInterfaces').abspath
-import sys
-sys.modules['comtypes.gen']=comtypes.gen=__import__("comInterfaces",globals(),locals(),[])
 
 COM_INTERFACES = {
 	"IAccessible2Lib.py": "typelibs/ia2.tlb",
diff --git a/source/comtypesMonkeyPatches.py b/source/comtypesMonkeyPatches.py
index c5031c13f6c..c599c475ea4 100644
--- a/source/comtypesMonkeyPatches.py
+++ b/source/comtypesMonkeyPatches.py
@@ -1,10 +1,12 @@
-#A part of NonVisual Desktop Access (NVDA)
-#Copyright (C) 2009-2016 NV Access Limited
-#This file is covered by the GNU General Public License.
-#See the file COPYING for more details.
+# A part of NonVisual Desktop Access (NVDA)
+# Copyright (C) 2009-2019 NV Access Limited, Babbage B.V.
+# This file is covered by the GNU General Public License.
+# See the file COPYING for more details.
 
 import ctypes
 import _ctypes
+import importlib
+import comtypes.client._generate
 
 # A version of ctypes.WINFUNCTYPE 
 # that produces a WinFunctionType class whose instance will convert COMError into a CallCancelled exception when called as a function.
@@ -125,3 +127,15 @@ def _check_version(actual):
 	if actual != required:
 		raise ImportError("Wrong version")
 comtypes._check_version = _check_version
+
+
+# Monkeypatch comtypes to clear the importlib cache when importing a new module
+old_my_import = comtypes.client._generate._my_import
+
+
+def new_my_import(fullname):
+	importlib.invalidate_caches()
+	return old_my_import(fullname)
+
+
+comtypes.client._generate._my_import = new_my_import