diff --git a/src/arg_desc.jl b/src/arg_desc.jl
index 45dcaaa5..64ce5b93 100644
--- a/src/arg_desc.jl
+++ b/src/arg_desc.jl
@@ -117,7 +117,7 @@ const _arg_desc = KW(
 :scale     				  => "Symbol. Scale of the axis: `:none`, `:ln`, `:log2`, `:log10`",
 :rotation  				  => "Number. Degrees rotation of tick labels.",
 :flip      				  => "Bool.  Should we flip (reverse) the axis?",
-:formatter 				  => "Function, :scientific, or :auto. A method which converts a number to a string for tick labeling.",
+:formatter 				  => "Function, :scientific, :plain or :auto. A method which converts a number to a string for tick labeling.",
 :tickfontfamily           => "String or Symbol. Font family of tick labels.",
 :tickfontsize             => "Integer. Font pointsize of tick labels.",
 :tickfonthalign           => "Symbol. Font horizontal alignment of tick labels: :hcenter, :left, :right or :center",