diff --git a/README.md b/README.md
index 34b4f3d..dd76c75 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 Whalesong
 =========
 
+IMPORTANT: Use -j 1 to build Whalesong (this turns off parallel builds)
+
 This fork of Whalesong differs from dyoo/whalesong in the following ways:
 
   * Builds on latest release of Racket