diff --git a/fish_prompt.fish b/fish_prompt.fish
index d71248e..ce61572 100644
--- a/fish_prompt.fish
+++ b/fish_prompt.fish
@@ -292,7 +292,7 @@ function __bobthefish_prompt_vagrant_vmware -S -d 'Display VMWare Vagrant status
   set_color normal
 end
 
-function __bobthefish_prompt_docker -S
+function __bobthefish_prompt_docker -S -d 'Show docker machine name'
     [ "$theme_display_docker_machine" = 'no' -o -z "$DOCKER_MACHINE_NAME" ]; and return
     __bobthefish_start_segment $__bobthefish_vagrant fff --bold
     echo -ns $DOCKER_MACHINE_NAME ' '