diff --git a/src/args.jl b/src/args.jl
index 6afdd66b..b305d613 100644
--- a/src/args.jl
+++ b/src/args.jl
@@ -80,9 +80,13 @@ const _typeAliases = Dict{Symbol,Symbol}(
 
 add_non_underscore_aliases!(_typeAliases)
 
-like_histogram(seriestype::Symbol) = seriestype in (:histogram, :barhist, :barbins)
-like_line(seriestype::Symbol)      = seriestype in (:line, :path, :steppre, :steppost)
-like_surface(seriestype::Symbol)   = seriestype in (:contour, :contourf, :contour3d, :heatmap, :surface, :wireframe, :image)
+const _histogram_like = [:histogram, :barhist, :barbins]
+const _line_like = [:line, :path, :steppre, :steppost]
+const _surface_like = [:contour, :contourf, :contour3d, :heatmap, :surface, :wireframe, :image]
+
+like_histogram(seriestype::Symbol) = seriestype in _histogram_like
+like_line(seriestype::Symbol)      = seriestype in _line_like
+like_surface(seriestype::Symbol)   = seriestype in _surface_like
 
 is3d(seriestype::Symbol) = seriestype in _3dTypes
 is3d(series::Series) = is3d(series.d)