diff --git a/appveyor.yml b/appveyor.yml
index 2e9b9d6..2618f69 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -47,6 +47,8 @@
 - python -m pip --version
 # Install Mako
 - python -m pip install --egg Mako
+# Install pywin32 extensions, needed by SCons
+- python -m pip install pypiwin32
 # Install SCons
 - python -m pip install --egg scons==2.4.1
 - scons --version