diff --git a/src/backends/gr.jl b/src/backends/gr.jl
index 0c2253fe..720e52a5 100644
--- a/src/backends/gr.jl
+++ b/src/backends/gr.jl
@@ -1103,10 +1103,10 @@ function gr_display(sp::Subplot{GRBackend}, w, h, viewport_canvas)
             GR.setspace(zmin, zmax, 0, 90)
             grad = isa(series[:fillcolor], ColorGradient) ? series[:fillcolor] : cgrad()
             colors = [plot_color(grad[clamp((zi-zmin) / (zmax-zmin), 0, 1)], series[:fillalpha]) for zi=z]
-            rgba = map(c -> UInt32( round(Int, alpha(c) * 255) << 24 +
-                                    round(Int,  blue(c) * 255) << 16 +
-                                    round(Int, green(c) * 255) << 8  +
-                                    round(Int,   red(c) * 255) ), colors)
+            rgba = map(c -> UInt32( round(UInt, alpha(c) * 255) << 24 +
+                                    round(UInt,  blue(c) * 255) << 16 +
+                                    round(UInt, green(c) * 255) << 8  +
+                                    round(UInt,   red(c) * 255) ), colors)
             w, h = length(x), length(y)
             GR.drawimage(xmin, xmax, ymax, ymin, w, h, rgba)
 
@@ -1210,12 +1210,12 @@ function gr_display(sp::Subplot{GRBackend}, w, h, viewport_canvas)
             xmin, xmax = ignorenan_extrema(series[:x]); ymin, ymax = ignorenan_extrema(series[:y])
             if eltype(z) <: Colors.AbstractGray
                 grey = round.(UInt8, float(z) * 255)
-                rgba = map(c -> UInt32( 0xff000000 + Int(c)<<16 + Int(c)<<8 + Int(c) ), grey)
+                rgba = map(c -> UInt32( 0xff000000 + UInt(c)<<16 + UInt(c)<<8 + UInt(c) ), grey)
             else
-                rgba = map(c -> UInt32( round(Int, alpha(c) * 255) << 24 +
-                                        round(Int,  blue(c) * 255) << 16 +
-                                        round(Int, green(c) * 255) << 8  +
-                                        round(Int,   red(c) * 255) ), z)
+                rgba = map(c -> UInt32( round(UInt, alpha(c) * 255) << 24 +
+                                        round(UInt,  blue(c) * 255) << 16 +
+                                        round(UInt, green(c) * 255) << 8  +
+                                        round(UInt,   red(c) * 255) ), z)
             end
             GR.drawimage(xmin, xmax, ymax, ymin, w, h, rgba)
         end