diff --git a/BUILDING b/BUILDING
index a400f468cf10be9283e16897f53d532089402ce5..089edeef8844b1f1e0a5f8caf57f10bc72de0168 100644
--- a/BUILDING
+++ b/BUILDING
@@ -635,7 +635,11 @@ same file system, via NFS or something else.
    x86/linux is in src/tools/cross-scripts/cross-ppc-x86.lisp.
 
 3. Build the cross compiler and target, as above, using the specified
-   cross-compile script.
+   cross-compile script:
+
+        src/tools/cross-build-world.sh x86-target x86-cross cross.lisp [ppc binary]
+
+   where cross.lisp is the cross-compile script from 2) above.
 
 4. Everything has now been compiled for the x86/linux target.  We need
    to compile the C code for x86 and create a lisp.core from the