diff --git a/README.md b/README.md
index 511c25a0..18007f5b 100644
--- a/README.md
+++ b/README.md
@@ -797,6 +797,24 @@ class Vehicle
 end
 ```
 
+#### Transition labels
+
+If you would prefer a custom label on a graphviz generated graph, specify
+the `:graph_label` option on the transition statement.
+
+For example:
+
+```ruby
+
+class Vehicle
+  state_machine :initial => :parked do
+
+  state :parked do
+    transition :to => :idling, :on => [:ignite, :shift_up], :if => :seatbelt_on?, :graph_label => "Seatbelt is ON"
+  end
+end
+```
+
 #### Transition context
 
 Some flexibility is provided around the context in which transitions can be
diff --git a/lib/state_machine/branch.rb b/lib/state_machine/branch.rb
index 56c5cafe..2d952acd 100644
--- a/lib/state_machine/branch.rb
+++ b/lib/state_machine/branch.rb
@@ -29,12 +29,16 @@ class Branch
     # * +from+ / +except_from+
     # * +to+ / +except_to+
     attr_reader :known_states
-    
+   
+    # An optional, custom, label to add to the graph when drawing the branch.
+    attr_reader :graph_label
+   
     # Creates a new branch
     def initialize(options = {}) #:nodoc:
       # Build conditionals
       @if_condition = options.delete(:if)
       @unless_condition = options.delete(:unless)
+      @graph_label      = options.delete(:graph_label)
       
       # Build event requirement
       @event_requirement = build_matcher(options, :on, :except_on)
diff --git a/lib/state_machine/event.rb b/lib/state_machine/event.rb
index 6ddaa7db..c8efc720 100644
--- a/lib/state_machine/event.rb
+++ b/lib/state_machine/event.rb
@@ -194,7 +194,7 @@ def reset
       @branches = []
       @known_states = []
     end
-    
+   
     # Draws a representation of this event on the given graph.  This will
     # create 1 or more edges on the graph for each branch (i.e. transition)
     # configured.
@@ -205,12 +205,18 @@ def reset
     def draw(graph, options = {})
       valid_states = machine.states.by_priority.map {|state| state.name}
       branches.each do |branch|
-        branch.draw(graph, options[:human_name] ? human_name : name, valid_states)
+        branch.draw(graph, graph_label(branch, options), valid_states)
       end
       
       true
     end
     
+    def graph_label(branch, options = {})
+       graph_label_name = (options[:human_name] ? human_name : name).to_s
+
+       branch.graph_label ? branch.graph_label : graph_label_name
+    end
+    
     # Generates a nicely formatted description of this event's contents.
     # 
     # For example,
diff --git a/lib/state_machine/graph.rb b/lib/state_machine/graph.rb
index c73a56ce..ef9497c0 100644
--- a/lib/state_machine/graph.rb
+++ b/lib/state_machine/graph.rb
@@ -86,7 +86,7 @@ def v0_api?
     
     # The ruby-graphviz version data
     def version
-      Constants::RGV_VERSION.split('.')
+      GraphViz::Constants::RGV_VERSION.split('.')
     end
   end
 end
diff --git a/state_machine.gemspec b/state_machine.gemspec
index 1b7614b6..164f4143 100644
--- a/state_machine.gemspec
+++ b/state_machine.gemspec
@@ -17,6 +17,8 @@ Gem::Specification.new do |s|
   s.extra_rdoc_files  = %w(README.md CHANGELOG.md LICENSE)
   
   s.add_development_dependency("rake")
+  s.add_development_dependency("test-unit")
   s.add_development_dependency("simplecov")
+  s.add_development_dependency("ruby-graphviz")
   s.add_development_dependency("appraisal", "~> 0.5.0")
 end
diff --git a/test/unit/event_test.rb b/test/unit/event_test.rb
index 1bf92cc4..7fe8306f 100644
--- a/test/unit/event_test.rb
+++ b/test/unit/event_test.rb
@@ -1170,6 +1170,28 @@ def test_should_use_event_name_for_edge_label
     end
   end
   
+  class EventDrawingWithCustomBranchLabelTest < Test::Unit::TestCase
+    def setup
+      states = [:parked, :idling]
+      
+      @machine = StateMachine::Machine.new(Class.new, :initial => :parked)
+      @machine.other_states(*states)
+      
+      graph = StateMachine::Graph.new('test')
+      states.each {|state| graph.add_nodes(state.to_s)}
+      
+      @machine.events << @event = StateMachine::Event.new(@machine , :park, :human_name => 'Park')
+      @event.transition :parked => :idling, :graph_label => "extra graph label"
+      
+      @event.draw(graph, :human_name => true)
+      @edge = graph.get_edge_at_index(0)
+    end
+    
+    def test_should_use_event_human_name_for_edge_label
+      assert_equal 'extra graph label', @edge['label'].to_s.gsub('"', '')
+    end
+  end
+
   class EventDrawingWithHumanNameTest < Test::Unit::TestCase
     def setup
       states = [:parked, :idling]
diff --git a/test/unit/machine_test.rb b/test/unit/machine_test.rb
index 066fc1d5..8463f084 100644
--- a/test/unit/machine_test.rb
+++ b/test/unit/machine_test.rb
@@ -3261,7 +3261,7 @@ def test_should_allow_orientation_to_be_portrait
       assert_equal 'TB', graph['rankdir'].to_s.gsub('"', '')
     end
     
-    if Constants::RGV_VERSION != '0.9.0'
+    if GraphViz::Constants::RGV_VERSION != '0.9.0'
       def test_should_allow_human_names_to_be_displayed
         @machine.event :ignite, :human_name => 'Ignite'
         @machine.state :parked, :human_name => 'Parked'