diff --git a/appveyor.yml b/appveyor.yml
index fa72e21c..4c57f50e 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -4,6 +4,9 @@ install:
 - ps: 7z x embree.zip -oc:\
 build_script:
 - ps: >-
+    # for groff
+    $env:Path += ";C:\cygwin64\bin"
+
     mkdir cmakebuild
 
     cd cmakebuild