diff --git a/lib/git_tracker/commit_message.rb b/lib/git_tracker/commit_message.rb
index a380651..b0d3e38 100644
--- a/lib/git_tracker/commit_message.rb
+++ b/lib/git_tracker/commit_message.rb
@@ -5,9 +5,9 @@ def initialize(file)
       @file = file
     end
 
-    def contains?(pattern)
+    def mentions_story?(number)
       message = File.read(@file)
-      message.include?(pattern)
+      message =~ %r{\[\w*\s?##{number}]}
     end
 
   end
diff --git a/lib/git_tracker/prepare_commit_message.rb b/lib/git_tracker/prepare_commit_message.rb
index 124a0bb..4e02b16 100644
--- a/lib/git_tracker/prepare_commit_message.rb
+++ b/lib/git_tracker/prepare_commit_message.rb
@@ -19,7 +19,7 @@ def run
       story = story_number_from_branch
 
       message = CommitMessage.new(file)
-      exit if message.contains?("[##{story}]")
+      exit if message.mentions_story?(story)
       message.append!("[##{story}]")
     end
 
diff --git a/spec/git_tracker/commit_message_spec.rb b/spec/git_tracker/commit_message_spec.rb
index 54cb522..8778de8 100644
--- a/spec/git_tracker/commit_message_spec.rb
+++ b/spec/git_tracker/commit_message_spec.rb
@@ -8,7 +8,7 @@
     -> { GitTracker::CommitMessage.new }.should raise_error ArgumentError
   end
 
-  describe "#contains?" do
+  describe "#mentions_story?" do
     subject { described_class.new(file) }
     let(:file) { "COMMIT_EDITMSG" }
     before do
@@ -17,12 +17,17 @@
 
     context "commit message contains the special Pivotal Tracker story syntax" do
       let(:commit_message_text) { example_commit_message("[#8675309]") }
-      it { subject.should be_contains("[#8675309]") }
+      it { subject.should be_mentions_story("8675309") }
+
+      context "with state change" do
+        let(:commit_message_text) { example_commit_message("[Fixes #8675309]") }
+        it { subject.should be_mentions_story("8675309") }
+      end
     end
 
     context "commit message doesn't contain the special Pivotal Tracker story syntax" do
-      let(:commit_message_text) { example_commit_message("[#not_it]") }
-      it { subject.should_not be_contains("[#8675309]") }
+      let(:commit_message_text) { example_commit_message("#8675309") }
+      it { subject.should_not be_mentions_story("8675309") }
     end
   end
 
diff --git a/spec/git_tracker/prepare_commit_message_spec.rb b/spec/git_tracker/prepare_commit_message_spec.rb
index 8db8a4c..bffe303 100644
--- a/spec/git_tracker/prepare_commit_message_spec.rb
+++ b/spec/git_tracker/prepare_commit_message_spec.rb
@@ -46,7 +46,7 @@
 
     context "branch name with a Pivotal Tracker story number" do
       let(:story) { "8675309" }
-      let(:commit_message) { stub("CommitMessage", contains?: false) }
+      let(:commit_message) { stub("CommitMessage", mentions_story?: false) }
       before do
         GitTracker::CommitMessage.stub(:new) { commit_message }
       end
@@ -58,7 +58,7 @@
 
       context "number already mentioned in the commit message" do
         before do
-          commit_message.stub(:contains?).with("[#8675309]") { true }
+          commit_message.stub(:mentions_story?).with("8675309") { true }
         end
 
         it "exits without updating the commit message" do