diff --git a/buildstream/element.py b/buildstream/element.py
index 49cc934e1832286512d5963e96bd0ce2cf5a03d8..8eb8ee8cb3a99147983b38f684f1e4c4c7588a83 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -349,8 +349,8 @@ class Element(Plugin):
         generated script is run:
 
         - All element variables have been exported.
-        - The cwd is `self.get_variable('build_root')/self.normal_name`.
-        - $PREFIX is set to `self.get_variable('install_root')`.
+        - The cwd is `self.get_variable('build-root')/self.normal_name`.
+        - $PREFIX is set to `self.get_variable('install-root')`.
         - The directory indicated by $PREFIX is an empty directory.
 
         Files are expected to be installed to $PREFIX.