diff --git a/lib/array.rb b/lib/array.rb
index 6d00e9d..0be0869 100644
--- a/lib/array.rb
+++ b/lib/array.rb
@@ -12,7 +12,9 @@ def stepwise
   end
   def comparing_collect
     accumulator = [] # collect implementation copied from Rubinius
-    stepwise {|element1, element2| accumulator << element1 if yield(element1, element2)}
+    stepwise do |element1, element2|
+      accumulator << element1 if yield(element1, element2)
+    end
     accumulator.compact
   end
 end
diff --git a/lib/node_analysis.rb b/lib/node_analysis.rb
index 3037508..202cd12 100644
--- a/lib/node_analysis.rb
+++ b/lib/node_analysis.rb
@@ -18,7 +18,8 @@ def homonyms
     end
     def diff(threshold)
       @method_definitions.comparing_collect do |method_definition_1, method_definition_2|
-        threshold >= (method_definition_1.body - method_definition_2.body).size
+        next if method_definition_1.flatten.size < method_definition_2.flatten.size
+        threshold >= (method_definition_1.body.flatten - method_definition_2.body.flatten).size
       end
     end
   end
diff --git a/spec/diff_false_positives/app/models/post.rb b/spec/diff_false_positives/app/models/post.rb
new file mode 100644
index 0000000..35a77d6
--- /dev/null
+++ b/spec/diff_false_positives/app/models/post.rb
@@ -0,0 +1,5 @@
+class Post < ActiveRecord::Base
+  def recent
+    find(:all)
+  end
+end
diff --git a/spec/diff_false_positives/app/models/user.rb b/spec/diff_false_positives/app/models/user.rb
new file mode 100644
index 0000000..badd793
--- /dev/null
+++ b/spec/diff_false_positives/app/models/user.rb
@@ -0,0 +1,9 @@
+class User < ActiveRecord::Base
+  def login(credentials)
+    find(:first, :conditions => ["name = ? and password = ?", credentials[:name], credentials[:password]])
+  end
+
+  def dropdown
+    find(:all).collect { |u| [u.name, u.name] }
+  end
+end
diff --git a/spec/model_spec.rb b/spec/model_spec.rb
index 719f6c0..a3bc2d6 100644
--- a/spec/model_spec.rb
+++ b/spec/model_spec.rb
@@ -152,4 +152,12 @@
     @model.parse("spec/two_node_diff")
     @model.method_definitions[0].filename.should == "spec/two_node_diff/second_file.rb"
   end
+  it "doesn't return false positives for one-node diffs" do
+    @model.parse("spec/diff_false_positives")
+    @model.diff(1).should == []
+  end
+  it "doesn't return false positives for five-node diffs" do
+    @model.parse("spec/diff_false_positives")
+    @model.diff(5).should == []
+  end
 end