4 files changed, 20 insertions, 4 deletions
diff --git a/lib/axlsx/drawing/axes.rb b/lib/axlsx/drawing/axes.rb
index c3a8dd85..40364d10 100644
--- a/lib/axlsx/drawing/axes.rb
+++ b/lib/axlsx/drawing/axes.rb
@@ -5,9 +5,11 @@ module Axlsx
   class Axes
 
     # @param [Hash] options options used to generate axis each key
-    # should be an axis name like :val_axix and its value should be the
-    # class of the axis type to construct.
+    # should be an axis name like :val_axis and its value should be the
+    # class of the axis type to construct. The :cat_axis, if there is one,
+    # must come first (we assume a Ruby 1.9+ Hash or an OrderedHash).
     def initialize(options={})
+      raise(ArgumentError, "CatAxis must come first") if options.keys.include?(:cat_axis) && options.keys.first != :cat_axis
       options.each do |name, axis_class|
         add_axis(name, axis_class)
       end
diff --git a/lib/axlsx/drawing/bar_3D_chart.rb b/lib/axlsx/drawing/bar_3D_chart.rb
index 3315ad80..755f334c 100644
--- a/lib/axlsx/drawing/bar_3D_chart.rb
+++ b/lib/axlsx/drawing/bar_3D_chart.rb
@@ -142,10 +142,10 @@ module Axlsx
     end
 
     # A hash of axes used by this chart. Bar charts have a value and
-    # category axes specified via axex[:val_axes] and axes[:cat_axis]
+    # category axes specified via axes[:val_axes] and axes[:cat_axis]
     # @return [Axes]
     def axes
-     @axes ||= Axes.new(:val_axis => ValAxis, :cat_axis => CatAxis)
+     @axes ||= Axes.new(:cat_axis => CatAxis, :val_axis => ValAxis)
     end
   end
 end
diff --git a/test/drawing/tc_axes.rb b/test/drawing/tc_axes.rb
new file mode 100644
index 00000000..e3c26936
--- /dev/null
+++ b/test/drawing/tc_axes.rb
@@ -0,0 +1,8 @@
+require 'tc_helper.rb'
+
+class TestAxes < Test::Unit::TestCase
+  def test_constructor_requires_cat_axis_first
+    assert_raise(ArgumentError) { Axlsx::Axes.new(:val_axis => Axlsx::ValAxis, :cat_axis => Axlsx::CatAxis) }
+    assert_nothing_raised { Axlsx::Axes.new(:cat_axis => Axlsx::CatAxis, :val_axis => Axlsx::ValAxis) }
+  end
+end
+\ No newline at end of file
diff --git a/test/drawing/tc_bar_3D_chart.rb b/test/drawing/tc_bar_3D_chart.rb
index 3e1ff342..0cae7af6 100644
--- a/test/drawing/tc_bar_3D_chart.rb
+++ b/test/drawing/tc_bar_3D_chart.rb
@@ -62,4 +62,10 @@ class TestBar3DChart < Test::Unit::TestCase
     assert(errors.empty?, "error free validation")
   end
 
+  def test_to_xml_string_has_axes_in_correct_order
+    str = @chart.to_xml_string
+    cat_axis_position = str.index(@chart.axes[:cat_axis].id.to_s)
+    val_axis_position = str.index(@chart.axes[:val_axis].id.to_s)
+    assert(cat_axis_position < val_axis_position, "cat_axis must occur earlier than val_axis in the XML")
+  end
 end