diff --git a/README.md b/README.md
index e131ca4..7ad31db 100644
--- a/README.md
+++ b/README.md
@@ -119,7 +119,7 @@ The following environment variables are supported:
 
  * `WPA_ESSID`, `WPA_PASSWORD` and `WPA_COUNTRY` (Default: unset)
 
-   If these are set, they are use to configure `wpa_supplicant.conf`, so that the raspberry pi can automatically connect to a wifi network on first boot.
+   If these are set, they are use to configure `wpa_supplicant.conf`, so that the raspberry pi can automatically connect to a wifi network on first boot. If `WPA_ESSID` is set and `WPA_PASSWORD` is unset an unprotected wifi network will be configured.
 
  * `ENABLE_SSH` (Default: `0`)
 
@@ -277,14 +277,13 @@ maintenance and allows for more easy customization.
    enhancements, etc.  This is a base desktop system, with some development
    tools installed.
 
- - **Stage 4** - Raspbian system meant to fit on a 4GB card.  More development
+ - **Stage 4** - Normal Raspbian image. System meant to fit on a 4GB card.  More development
    tools, an email client, learning tools like Scratch, specialized packages
    like sonic-pi, system documentation, office productivity, etc.  This is the
    stage that installs all of the things that make Raspbian friendly to new
    users.
 
- - **Stage 5** - The official Raspbian Desktop image. Right now only adds
-   Mathematica.
+ - **Stage 5** - The Raspbian Full image.
 
 ### Stage specification
 
@@ -292,7 +291,7 @@ If you wish to build up to a specified stage (such as building up to stage 2
 for a lite system), place an empty file named `SKIP` in each of the `./stage`
 directories you wish not to include.
 
-Then add an empty file named `SKIP_IMAGES` to `./stage4` (if building up to stage 2) or
+Then add an empty file named `SKIP_IMAGES` to `./stage4` and `./stage5` (if building up to stage 2) or
 to `./stage2` (if building a minimal system).
 
 ```bash
diff --git a/build.sh b/build.sh
index b806562..a396b06 100755
--- a/build.sh
+++ b/build.sh
@@ -247,7 +247,7 @@ for EXPORT_DIR in ${EXPORT_DIRS}; do
 	fi
 done
 
-if [ -x postrun.sh ]; then
+if [ -x ${BASE_DIR}/postrun.sh ]; then
 	log "Begin postrun.sh"
 	cd "${BASE_DIR}"
 	./postrun.sh
diff --git a/stage2/02-net-tweaks/01-run.sh b/stage2/02-net-tweaks/01-run.sh
index 3ba2ef9..154e515 100755
--- a/stage2/02-net-tweaks/01-run.sh
+++ b/stage2/02-net-tweaks/01-run.sh
@@ -14,6 +14,14 @@ if [ -v WPA_ESSID ] && [ -v WPA_PASSWORD ]; then
 on_chroot <<EOF
 wpa_passphrase "${WPA_ESSID}" "${WPA_PASSWORD}" >> "/etc/wpa_supplicant/wpa_supplicant.conf"
 EOF
+elif [ -v WPA_ESSID ]; then
+cat >> "${ROOTFS_DIR}/etc/wpa_supplicant/wpa_supplicant.conf" << EOL
+
+network={
+	ssid="${WPA_ESSID}"
+	key_mgmt=NONE
+}
+EOL
 fi
 
 # Disable wifi on 5GHz models