diff --git a/appveyor.yml b/appveyor.yml
index 84832b7..0cd3671 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -78,6 +78,8 @@ build_script:
   # Patch the PyInstaller building\utils.py to avoid storing project path
   # names.
   - "pushd %PYTHON%\\Lib\\site-packages\\PyInstaller\\building && python -m patch %PROJDIR%\\hooks\\utils.py.diff && popd"
+  # Patch the PyInstall loader\pyiboot01_bootstrap.py to keep ctypes' patches a scope other than global
+  - "pushd %PYTHON%\\Lib\\site-packages\\PyInstaller\\loader && python -m patch %PROJDIR%\\hooks\\pyiboot01_bootstrap.py.diff && popd"
   - del /S /Q %PYTHON%\*.pyc >NUL
   - del /S /Q %PYTHON%\*.pyo >NUL
   # Save the artifact immediately
diff --git a/hooks/pyiboot01_bootstrap.py.diff b/hooks/pyiboot01_bootstrap.py.diff
new file mode 100644
index 0000000..866bf23
--- /dev/null
+++ b/hooks/pyiboot01_bootstrap.py.diff
@@ -0,0 +1,33 @@
+--- pyiboot01_bootstrap.py	2019-08-12 17:37:25.460219000 +1000
++++ pyiboot01_bootstrap.py	2019-08-13 18:10:32.084968800 +1000
+@@ -123,11 +123,12 @@
+ if sys.warnoptions:
+     import warnings
+ 
+-try:
++def _setup_ctypes():
+     import ctypes
+     import os
++    import sys
+     from ctypes import LibraryLoader, DEFAULT_MODE
+-
++    
+     def _frozen_name(name):
+         if name:
+             frozen_name = os.path.join(sys._MEIPASS, os.path.basename(name))
+@@ -186,6 +186,8 @@
+ 
+         ctypes.OleDLL = PyInstallerOleDLL
+         ctypes.oledll = LibraryLoader(PyInstallerOleDLL)
++try:
++    _setup_ctypes()
+ except ImportError:
+     pass
+ 
+@@ -213,4 +215,4 @@
+ # use-case, see issue #653.
+ if os.path.isdir(d):
+     for fn in os.listdir(d):
+-        sys.path.append(os.path.join(d, fn))
++        sys.path.append(os.path.join(d, fn)) 
+\ No newline at end of file
diff --git a/pyexe.py b/pyexe.py
index a9204f6..811a373 100644
--- a/pyexe.py
+++ b/pyexe.py
@@ -408,7 +408,7 @@ def skip(*args, **kwargs):
     # Generate the globals/locals environment
     globenv = {}
     for key in list(globals().keys()):
-        if key.startswith('_') and key != '_frozen_name':
+        if key.startswith('_') and not key in ['_frozen_name','_setup_ctypes']:
             globenv[key] = globals()[key]
     if RunFile:
         run_file(RunFile, RunFileArgv, SkipFirstLine, globenv)