diff --git a/www/hacking.html b/www/hacking.html
index e0d2ce4b72..978c99f141 100644
--- a/www/hacking.html
+++ b/www/hacking.html
@@ -185,6 +185,10 @@
  (path to llvm)/llvm/tools/clang/test
   </tt>
 
+  <p>For CMake builds e.g. on Windows with Visual Studio, you will need
+  to specify your build configuration (Debug, Release, etc.) via
+  <tt>--param=build_config=(build config)</tt>.</p>
+
   <p>To run a single test:</p>
   
   <tt>