diff --git a/.jenkins.d/README.md b/.jenkins.d/README.md
index 085e383..41812aa 100644
--- a/.jenkins.d/README.md
+++ b/.jenkins.d/README.md
@@ -32,3 +32,5 @@
 
 - `CACHE_DIR`: the variable defines a path to folder containing cached files from previous builds,
   e.g., a compiled version of ndn-cxx library.  If not set, `/tmp` is used.
+
+- `WAF_JOBS`: number of parallel build jobs used by waf, defaults to 1.