diff --git a/README b/README
index 09765fb..ff1832e 100644
--- a/README
+++ b/README
@@ -240,6 +240,7 @@ Note: These steps should be done with 64 bits support.
   [chroot32] # cp -r /usr/share/archiso/configs/releng /tmp
   [chroot32] # cd /tmp/releng
   [chroot32] # ./build.sh all_iso_single
+  [chroot32] # ./build.sh purge_single #optional
 
 * Enter 64 bits chroot enviroment then build core and netinstall single images.
 
@@ -248,9 +249,10 @@ Note: These steps should be done with 64 bits support.
   [chroot64] # cp -r /usr/share/archiso/configs/releng /tmp
   [chroot64] # cd /tmp/releng
   [chroot64] # ./build.sh all_iso_single
+  [chroot64] # ./build.sh purge_single #optional
 
 * Build core and netinstall dual images from any of the chroot enviroments.
 
-  [host64] mkarchroot -r bash /tmp/chroot64
+  [host64] # mkarchroot -r bash /tmp/chroot64
   [chroot64] # cd /tmp/releng
   [chroot64] # ./build.sh all_iso_dual
diff --git a/configs/releng/build.sh b/configs/releng/build.sh
index 135cc03..e75edb7 100755
--- a/configs/releng/build.sh
+++ b/configs/releng/build.sh
@@ -215,8 +215,8 @@ make_dual() {
 
 _usage ()
 {
-    echo "usage ${0##*/} net_iso_single | core_iso_single | all_iso_single | clean_single"
-    echo "               net_iso_dual   | core_iso_dual   | all_iso_dual   | clean_dual"
+    echo "usage ${0##*/} net_iso_single | core_iso_single | all_iso_single | purge_single | clean_single"
+    echo "               net_iso_dual   | core_iso_dual   | all_iso_dual   | purge_dual   | clean_dual"
     echo
     exit ${1}
 }
@@ -280,6 +280,20 @@ case "${command_name}" in
         make_dual netinstall
         make_dual core
         ;;
+    purge_single)
+        if [[ -d ${work_dir} ]]; then
+            find ${work_dir} -mindepth 1 -maxdepth 1 \
+                ! -path ${work_dir}/iso -prune \
+                | xargs rm -rf
+        fi
+        ;;
+    purge_dual)
+        if [[ -d ${work_dir}/dual ]]; then
+            find ${work_dir}/dual -mindepth 1 -maxdepth 1 \
+                ! -path ${work_dir}/dual/iso -prune \
+                | xargs rm -rf
+        fi
+        ;;
     clean_single)
         rm -rf ${work_dir}
         rm -f ${name}-${version}-*-${arch}.iso