diff --git a/src/backends/gr.jl b/src/backends/gr.jl
index c17df76e..b4622145 100644
--- a/src/backends/gr.jl
+++ b/src/backends/gr.jl
@@ -944,7 +944,7 @@ function gr_display(sp::Subplot{GRBackend}, w, h, viewport_canvas)
 
         elseif st == :image
             z = transpose_z(series, series[:z].surf, true)
-            h, w = size(z)
+            w, h = size(z)
             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)