diff --git a/tools/windows/setup_cross_compilation_env.sh b/tools/windows/setup_cross_compilation_env.sh
index 148316da3..051795003 100755
--- a/tools/windows/setup_cross_compilation_env.sh
+++ b/tools/windows/setup_cross_compilation_env.sh
@@ -9,12 +9,12 @@ set -e
 #
 # SETUP -- adjust these variables if neccessary.
 # You can also override them from the command line:
-# INSTALL_DIR=/opt/mingw ./setup_cross_compilation_env.sh
+# INSTALL_DIR=/opt/mingw ARCHITECTURE=32 ./setup_cross_compilation_env.sh
 #
 
 # This defaults to a 64bit executable. If you need a 32bit executable
 # then change ARCHITECTURE to 32.
-ARCHITECTURE=64
+ARCHITECTURE=${ARCHITECTURE:-64}
 # Installation defaults to ~/mxe.
 INSTALL_DIR=${INSTALL_DIR:-$HOME/mxe}
 # Leave PARALLEL empty if you want the script to use all of your CPU