diff --git a/docs/building/build-1.8.0.md b/docs/building/build-1.8.0.md
index 353519cdb8a..c8881619dba 100644
--- a/docs/building/build-1.8.0.md
+++ b/docs/building/build-1.8.0.md
@@ -8,6 +8,8 @@ You must have:
 * Linux or macOS.
 * Docker installed.
 * 14 GB memory available and configured in Docker.
+* To get reproducible artifacts, [umask](https://en.wikipedia.org/wiki/Umask) command without parameters should 
+produce `0022` or `022` output.
 
 ## Set environment variables