diff --git a/bypy/macos.conf b/bypy/macos.conf
index a84521e76f..5a9ae75ba2 100644
--- a/bypy/macos.conf
+++ b/bypy/macos.conf
@@ -1,3 +1,6 @@
+# Requires installation of XCode 10.2 and Python 3.7 and 
+# python3 -m pip install certifi
+
 vm_name 'calibre-macos-build'
 root '/Users/Shared/calibre-build'
 python '/Library/Frameworks/Python.framework/Versions/3.7/bin/python3'
diff --git a/bypy/windows.conf b/bypy/windows.conf
index e0d54a7ffb..4c78912984 100644
--- a/bypy/windows.conf
+++ b/bypy/windows.conf
@@ -1,3 +1,6 @@
+# Requires installation of Visual Studio 2017 Community Edition and Python 3.7
+# python.exe -m pip install certifi
+
 vm_name 'calibre-windows-build'
 root 'C:/r'
 python 'C:/py/python.exe'