diff --git a/bin/omz.sh b/bin/omz.sh
index d73ab95ac..4a4d2f4ec 100755
--- a/bin/omz.sh
+++ b/bin/omz.sh
@@ -2,40 +2,33 @@
 
 function omz_usage() {
     echo "Oh My Zsh command line tool. Available commands:"
-    echo "   plugin NAME  Enable plugin specified by NAME"
-    echo "   theme        Choose theme"
-    echo "   upgrade      Upgrade Oh My Zsh"
-    echo "   uninstall    Remove Oh My Zsh :("
-    echo "   help         Show this help"
+    echo "  plugin         Manage plugins"
+    echo "  theme_chooser  Preview themes"
+    echo "  upgrade        Upgrade Oh My Zsh"
+    echo "  uninstall      Remove Oh My Zsh :("
+    echo "  help           Show this help"
 }
 
 COMMAND=$1
 
 case $COMMAND in
 
-    plugin )
+    plugin )  # we need source to enable autocompletion
         shift 1
-        source $ZSH/tools/omz-plugin.sh $@
-        ;;
-
-    theme )
-        zsh $ZSH/tools/theme_chooser.sh
-        ;;
-
-    upgrade )
-        zsh $ZSH/tools/upgrade.sh
-        ;;
-
-    uninstall )
-        zsh $ZSH/tools/uninstall.sh
-        ;;
-
-    help )
-        omz_usage
+        source $ZSH/tools/$COMMAND.sh $@
         ;;
 
     * )
-        omz_usage
+        shift 1
+
+        if [ -x $ZSH/tools/$COMMAND.sh ]; then
+            zsh $ZSH/tools/$COMMAND.sh $@
+        else
+            omz_usage
+        fi
         ;;
 
+    '' | help )
+        omz_usage ;;
+
 esac
diff --git a/tools/_omz.sh b/tools/_omz.sh
index af4a83de6..e3909c8ab 100644
--- a/tools/_omz.sh
+++ b/tools/_omz.sh
@@ -7,8 +7,8 @@ _omz_all_plugins() {
 
 local -a _1st_arguments
 _1st_arguments=(
-    'plugin:Enable plugin'
-    'theme:Choose theme'
+    'plugin:Manage plugins'
+    'theme_chooser:Preview themes'
     'upgrade:Upgrade Oh My Zsh'
     'uninstall:Remove Oh My Zsh :('
 )
diff --git a/tools/upgrade.sh b/tools/upgrade.sh
old mode 100644
new mode 100755