diff --git a/appveyor.yml b/appveyor.yml
index b65b5da..4f0ebe9 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -23,6 +23,10 @@
       configuration: Debug
       OPENSSL64DIR: C:\OpenSSL-v11-Win64
 
+before_build:
+  - ps: git submodule init
+  - ps: git submodule update
+
 build:
   parallel: true
   project: picotlsvs\picotlsvs.sln