diff --git a/src/geom/hvabline.jl b/src/geom/hvabline.jl
index 501ece73d..70f5248a1 100755
--- a/src/geom/hvabline.jl
+++ b/src/geom/hvabline.jl
@@ -157,17 +157,15 @@ function render(geom::ABLineGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetic
     # the line extends to the edges of the graph.
 
     if typeof(aes.y) <: Array{Function}
-        low, high = aes.xmin[1], aes.xmax[1]
+        lowx, highx = aes.xmin[1], aes.xmax[1]
     else
-        xextrema = extrema(aes.x)
-        yextrema = extrema(aes.y)
-        low = min(xextrema[1], yextrema[1])
-        high = max(xextrema[2], yextrema[2])
+        lowx, highx = extrema(aes.x)
     end
 
-    range = high-low
-    x0 = low-range
-    x1 = high+range
+    # extending the line to width 3 times x-range of data should be enough
+    rangex = highx - lowx
+    x0 = lowx - rangex
+    x1 = highx + rangex
 
     y0s = [x0 * m + b for (m,b) in zip(aes.slope, aes.intercept)]
     y1s = [x1 * m + b for (m,b) in zip(aes.slope, aes.intercept)]
diff --git a/src/scale.jl b/src/scale.jl
index 4936e3e9a..c0ed842ea 100644
--- a/src/scale.jl
+++ b/src/scale.jl
@@ -600,26 +600,13 @@ const color_continuous_gradient = color_continuous  ### WHY HAVE THIS ALIAS?
 
 function apply_scale(scale::ContinuousColorScale,
                      aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
-    cmin, cmax = Inf, -Inf
-    for data in datas
-        data.color === nothing && continue
-
-        for c in data.color
-            ismissing(c) && continue
-
-            c = convert(Float64, c)
-            if c < cmin
-                cmin = c
-            end
-
-            if c > cmax
-                cmax = c
-            end
-        end
+    cdata = skipmissing(Iterators.flatten(i.color for i in datas if i.color != nothing))
+    if !isempty(cdata)
+      cmin, cmax = extrema(cdata)
+    else
+        return
     end
 
-    (cmin == Inf || cmax == -Inf) && return
-
     if scale.minvalue != nothing
         cmin = scale.minvalue
     end
@@ -671,11 +658,11 @@ function apply_scale(scale::ContinuousColorScale,
 end
 
 function apply_scale_typed!(ds, field, scale::ContinuousColorScale,
-                            cmin::Float64, cspan::Float64)
+                            cmin, cspan)
     for (i, d) in enumerate(field)
         if isconcrete(d)
             ds[i] = convert(RGB{Float32},
-                        scale.f((convert(Float64, scale.trans.f(d)) - cmin) / cspan))
+                        scale.f((scale.trans.f(d) - cmin) / cspan))
         else
             ds[i] = missing
         end
diff --git a/src/ticks.jl b/src/ticks.jl
index 3eee01765..aae6954d5 100644
--- a/src/ticks.jl
+++ b/src/ticks.jl
@@ -2,7 +2,7 @@
 # little opaque because I want to avoid assuming the log function is defined
 # over typeof(xspan)
 function bounding_order_of_magnitude(xspan::DT) where DT
-    one_dt = convert(DT, one(DT))
+    one_dt = oneunit(DT)
 
     a = 1
     step = 1
@@ -69,7 +69,7 @@ function optimize_ticks_typed(x_min::T, x_max::T, extend_ticks,
                            granularity_weight::Float64, simplicity_weight::Float64,
                            coverage_weight::Float64, niceness_weight::Float64,
                            strict_span) where T
-    one_t = convert(T, one(T))
+    one_t = oneunit(T)
     if x_max - x_min < eps()*one_t
         R = typeof(1.0 * one_t)
         return R[x_min], x_min - one_t, x_min + one_t
diff --git a/test/REQUIRE b/test/REQUIRE
index 91456cd49..60d3fb990 100644
--- a/test/REQUIRE
+++ b/test/REQUIRE
@@ -2,3 +2,4 @@ DataFrames
 RDatasets
 Cairo
 CSV
+Unitful
diff --git a/test/testscripts/percent.jl b/test/testscripts/percent.jl
index 48d3a79c2..49b8c0bdb 100644
--- a/test/testscripts/percent.jl
+++ b/test/testscripts/percent.jl
@@ -2,7 +2,7 @@ using Gadfly
 
 set_default_plot_size(6inch, 6inch)
 
-import Base: show, +, -, /, *, isless, one, zero, isfinite
+import Base: convert, show, +, -, /, *, isless, one, zero, isfinite
 
 struct Percent
     value::Float64
@@ -23,6 +23,7 @@ isless(a::Percent, b::Percent) = isless(a.value, b.value)
 one(::Type{Percent}) = Percent(0.01)
 zero(::Type{Percent}) = Percent(0.0)
 isfinite(a::Percent) = isfinite(a.value)
+convert(::Type{Float64}, x::Percent) = x.value
 show(io::IO, p::Percent) = print(io, round(100 * p.value, digits=4), "%")
 
 y=[Percent(0.1), Percent(0.2), Percent(0.3)]
diff --git a/test/testscripts/unitful_basic.jl b/test/testscripts/unitful_basic.jl
new file mode 100644
index 000000000..8324ac22f
--- /dev/null
+++ b/test/testscripts/unitful_basic.jl
@@ -0,0 +1,19 @@
+using Unitful, Gadfly, DataFrames
+
+a = -9.81u"m/s^2"
+t = (1:0.5:10)u"s"
+v = a .* t
+v2 = v .+ 2u"m/s"
+h = 0.5 * a .* t.^2
+df = DataFrame(time=t, velocity=v, position=h,
+               unitlesst=ustrip.(t), unitlessv=ustrip.(v), unitlessh=ustrip.(h),
+               position2=reverse(h))
+
+# test basics of point/line plots with Unitful
+gridstack(reshape([plot(df, x=:time, y=:velocity),
+                   plot(df, x=:position, y=:time),
+                   plot(df, x=:unitlesst, y=:velocity),
+                   plot(df, x=:time, y=:unitlessh),
+                   plot(df, x=:time, y=:position, Geom.line),
+                   plot(df, layer(x=:time, y=:position, Geom.line),
+                        layer(x=:time, y=:position2))], (3,2)))
diff --git a/test/testscripts/unitful_color.jl b/test/testscripts/unitful_color.jl
new file mode 100644
index 000000000..3a2e99229
--- /dev/null
+++ b/test/testscripts/unitful_color.jl
@@ -0,0 +1,15 @@
+using Unitful, Gadfly, DataFrames
+
+a = -9.81u"m/s^2"
+t = (1:0.5:10)u"s"
+v = a .* t
+v2 = v .+ 2u"m/s"
+h = 0.5 * a .* t.^2
+df = DataFrame(time=t, velocity=v, position=h,
+               unitlesst=ustrip.(t), unitlessv=ustrip.(v), unitlessh=ustrip.(h),
+               position2=reverse(h))
+
+# Test that it's possible to categorize by Unitful quantities
+vstack(plot(df, x=:time, y=:position, color=:velocity, Geom.point),
+       plot(df, x=:time, y=:velocity, color=:position, Geom.line),
+       plot(df, x=:time, y=:position, color=:unitlessv))
diff --git a/test/testscripts/unitful_geoms.jl b/test/testscripts/unitful_geoms.jl
new file mode 100644
index 000000000..1787be49c
--- /dev/null
+++ b/test/testscripts/unitful_geoms.jl
@@ -0,0 +1,26 @@
+using Unitful, Gadfly, DataFrames
+
+a = -9.81u"m/s^2"
+t = (1:0.5:10)u"s"
+v = a .* t
+v2 = v .+ 2u"m/s"
+h = 0.5 * a .* t.^2
+df = DataFrame(time=t, velocity=v, position=h,
+               unitlesst=ustrip.(t), unitlessv=ustrip.(v), unitlessh=ustrip.(h),
+               position2=reverse(h))
+
+# Test various geometries with Unitful
+p1 = plot(df, x=:time, y=:velocity, Geom.bar)
+p2 = plot(df, x=:time, y=:position, Geom.point,
+          intercept=[-80u"m"], slope=[10u"m/s"], Geom.abline)
+p3 = plot(df, x=:time, y=:velocity, Geom.line,
+          yintercept=[-20u"m/s", -40u"m/s"], Geom.hline)
+# Currently explicitly stated that it loess and lm require arrays of plain numbers
+#p4 = plot(df, x=:time, y=:position, Geom.point,
+#          Geom.smooth(method=:loess, smoothing=0.2))
+p4 = plot(df, x=:position, y=:velocity, Geom.path)
+p5 = plot(df, x=:time, y=:position, Geom.step,
+          xintercept=[3u"s", 8u"s"], Geom.vline)
+p6 = plot(df, layer(x=:time, y=:position, Geom.line),
+          layer(x=:time, y=:position2, Geom.bar))
+gridstack(reshape([p1,p2,p3,p4,p5,p6], (2,3)))