diff --git a/docs/example_generation.jl b/docs/example_generation.jl
index d6699633..2318d250 100644
--- a/docs/example_generation.jl
+++ b/docs/example_generation.jl
@@ -11,8 +11,8 @@ doc"""
 Holds all data needed for a documentation example... header, description, and plotting expression (Expr)
 """
 type PlotExample
-  header::String
-  desc::String
+  header::AbstractString
+  desc::AbstractString
   exprs::Vector{Expr}
 end
 
diff --git a/src/Plots.jl b/src/Plots.jl
index 8776e026..74c5bf57 100644
--- a/src/Plots.jl
+++ b/src/Plots.jl
@@ -87,7 +87,7 @@ ohlc!(args...; kw...)      = plot!(args...; kw..., linetype = :ohlc)
 
 savepng(args...; kw...) = savepng(currentPlot(), args...; kw...)
 savepng(plt::PlottingObject, args...; kw...) = savepng(plt.plotter, plt, args...; kw...)
-savepng(::PlottingPackage, plt::PlottingObject, fn::String, args...) = error("unsupported")  # fallback so multiple dispatch doesn't get confused if it's missing
+savepng(::PlottingPackage, plt::PlottingObject, fn::AbstractString, args...) = error("unsupported")  # fallback so multiple dispatch doesn't get confused if it's missing
 
 
 # ---------------------------------------------------------
diff --git a/src/args.jl b/src/args.jl
index ef9ba397..b84abab5 100644
--- a/src/args.jl
+++ b/src/args.jl
@@ -111,7 +111,7 @@ function getRGBColor(c, n::Int = 0)
   if isa(c, Symbol)
     c = string(c)
   end
-  if isa(c, String)
+  if isa(c, AbstractString)
     c = parse(Colorant, c)
   end
 
diff --git a/src/backends/gadfly.jl b/src/backends/gadfly.jl
index cb9cc135..fd8871cf 100644
--- a/src/backends/gadfly.jl
+++ b/src/backends/gadfly.jl
@@ -182,7 +182,7 @@ end
 
 # -------------------------------
 
-function savepng(::GadflyPackage, plt::PlottingObject, fn::String;
+function savepng(::GadflyPackage, plt::PlottingObject, fn::AbstractString;
                                     w = 6 * Gadfly.inch,
                                     h = 4 * Gadfly.inch)
   o = getGadflyContext(plt.plotter, plt)
diff --git a/src/backends/immerse.jl b/src/backends/immerse.jl
index 7a012b8d..684a85bc 100644
--- a/src/backends/immerse.jl
+++ b/src/backends/immerse.jl
@@ -63,7 +63,7 @@ end
 getGadflyContext(::ImmersePackage, plt::Plot) = plt.o[2]
 getGadflyContext(::ImmersePackage, subplt::Subplot) = buildGadflySubplotContext(subplt)
 
-function savepng(::ImmersePackage, plt::PlottingObject, fn::String;
+function savepng(::ImmersePackage, plt::PlottingObject, fn::AbstractString;
                                     w = 6 * Immerse.inch,
                                     h = 4 * Immerse.inch)
   gctx = getGadflyContext(plt.plotter, plt)
diff --git a/src/backends/pyplot.jl b/src/backends/pyplot.jl
index 69eb378d..e2e899ca 100644
--- a/src/backends/pyplot.jl
+++ b/src/backends/pyplot.jl
@@ -47,7 +47,7 @@ function getPyPlotMarker(marker::Symbol)
 end
 
 # pass through
-function getPyPlotMarker(marker::String)
+function getPyPlotMarker(marker::AbstractString)
   @assert length(marker) == 1
   marker
 end
@@ -226,7 +226,7 @@ end
 
 # -------------------------------
 
-function savepng(::PyPlotPackage, plt::PlottingObject, fn::String, args...)
+function savepng(::PyPlotPackage, plt::PlottingObject, fn::AbstractString, args...)
   addPyPlotLegend(plt)
   f = open(fn, "w")
   writemime(f, "image/png", plt.o)
diff --git a/src/backends/qwt.jl b/src/backends/qwt.jl
index 02c7303c..615ad426 100644
--- a/src/backends/qwt.jl
+++ b/src/backends/qwt.jl
@@ -50,7 +50,7 @@ end
 
 # -------------------------------
 
-savepng(::QwtPackage, plt::PlottingObject, fn::String, args...) = Qwt.savepng(plt.o, fn)
+savepng(::QwtPackage, plt::PlottingObject, fn::AbstractString, args...) = Qwt.savepng(plt.o, fn)
 
 # -------------------------------
 
diff --git a/src/backends/template.jl b/src/backends/template.jl
index bfeaa859..a6a28257 100644
--- a/src/backends/template.jl
+++ b/src/backends/template.jl
@@ -41,7 +41,7 @@ end
 
 # -------------------------------
 
-function savepng(::[PkgName]Package, plt::PlottingObject, fn::String; kw...)
+function savepng(::[PkgName]Package, plt::PlottingObject, fn::AbstractString; kw...)
   # TODO: save a PNG of the underlying plot/subplot object
 end
 
diff --git a/src/backends/unicodeplots.jl b/src/backends/unicodeplots.jl
index cd3f9307..73a20586 100644
--- a/src/backends/unicodeplots.jl
+++ b/src/backends/unicodeplots.jl
@@ -124,7 +124,7 @@ end
 
 # -------------------------------
 
-function savepng(::UnicodePlotsPackage, plt::PlottingObject, fn::String, args...)
+function savepng(::UnicodePlotsPackage, plt::PlottingObject, fn::AbstractString, args...)
 
   # make some whitespace and show the plot
   println("\n\n\n\n\n\n")
diff --git a/src/backends/winston.jl b/src/backends/winston.jl
index 93e1e426..c6f5b342 100644
--- a/src/backends/winston.jl
+++ b/src/backends/winston.jl
@@ -242,7 +242,7 @@ end
 
 # -------------------------------
 
-function savepng(::WinstonPackage, plt::PlottingObject, fn::String; kw...)
+function savepng(::WinstonPackage, plt::PlottingObject, fn::AbstractString; kw...)
   f = open(fn, "w")
   window, canvas, wplt = getWinstonItems(plt)
   addWinstonLegend(plt, wplt)