Index: readme.txt
===================================================================
--- readme.txt	(revision 4f3fe484e6e0b39b41d3eef2d9da1c103d7ccc47)
+++ readme.txt	(revision 8e1b1633c6a334db78a3162f8ec73ec97dfe8c03)
@@ -32,7 +32,7 @@
   https://www.freetype.org/
 
-Currently, we build the emulator code natively on Linux and OS X. The
+Currently, we build the emulator natively on Linux and OS X. The
 Windows version is cross-compiled on Linux using a x86_64-w64-mingw32
-toolchain.
+cross-toolchain.
 
 For Linux and OS X, our Makefile expects all of the above libraries to
@@ -91,5 +91,6 @@
   * We use "--prefix=/opt/sdl2-win" instead of "--prefix=/opt/sdl2",
     so that the Windows versions of the libraries go to a different
-    directory.
+    directory. That's where our Makefile expects to find them when
+    cross-building.
 
   * We additionally specify "--host=x86_64-w64-mingw32" to enable
@@ -100,5 +101,7 @@
   make buchla WIN=1
 
-from the top-level directory of this repository.
+from the top-level directory of this repository. Defining the "WIN"
+variable selects the cross-toolchain and "/opt/sdl2-win" as the
+library directory.