diff --git a/Library/Homebrew/rubocops/extend/formula_cop.rb b/Library/Homebrew/rubocops/extend/formula_cop.rb
index 94952d1f53..862dabfda4 100644
--- a/Library/Homebrew/rubocops/extend/formula_cop.rb
+++ b/Library/Homebrew/rubocops/extend/formula_cop.rb
@@ -297,6 +297,11 @@ module RuboCop
         true
       end
 
+      # Check if negation is present in the given node
+      def negated?(node)
+        method_called?(node, :!)
+      end
+
       # Return all the caveats' string nodes in an array
       def caveats_strings
         find_strings(find_method_def(@body, :caveats))
diff --git a/Library/Homebrew/rubocops/lines_cop.rb b/Library/Homebrew/rubocops/lines_cop.rb
index 4c82b42cf1..6c0c3ec736 100644
--- a/Library/Homebrew/rubocops/lines_cop.rb
+++ b/Library/Homebrew/rubocops/lines_cop.rb
@@ -288,15 +288,15 @@ module RuboCop
           end
 
           find_instance_method_call(body_node, :build, :with?) do |m|
-            next unless method_called?(m.parent, :!)
+            next unless negated?(m.parent)
             problem "Don't negate 'build.with?': use 'build.without?'"
           end
 
-          # find_instance_method_call(body_node, :build, :without?) do |m|
-          #   next unless negation?(m)
-          #   problem "Don't negate 'build.without?': use 'build.with?'"
-          # end
-          #
+          find_instance_method_call(body_node, :build, :without?) do |m|
+            next unless negated?(m.parent)
+            problem "Don't negate 'build.without?': use 'build.with?'"
+          end
+
           # find_instance_method_call(body_node, :build, :without?) do |m|
           #   arg = parameters(m).first
           #   next unless match = regex_match_group(arg, %r{-?-?without-(.*)})
diff --git a/Library/Homebrew/test/rubocops/lines_cop_spec.rb b/Library/Homebrew/test/rubocops/lines_cop_spec.rb
index 8e3f42adf6..e008349635 100644
--- a/Library/Homebrew/test/rubocops/lines_cop_spec.rb
+++ b/Library/Homebrew/test/rubocops/lines_cop_spec.rb
@@ -691,6 +691,30 @@ describe RuboCop::Cop::FormulaAudit::Miscellaneous do
         expect_offense(expected, actual)
       end
     end
+
+    it "with negated build.with?" do
+      source = <<-EOS.undent
+        class Foo < Formula
+          desc "foo"
+          url 'http://example.com/foo-1.0.tgz'
+          def post_install
+            return if !build.without? "bar"
+          end
+        end
+      EOS
+
+      expected_offenses = [{  message: "Don't negate 'build.without?': use 'build.with?'",
+                              severity: :convention,
+                              line: 5,
+                              column: 14,
+                              source: source }]
+
+      inspect_source(cop, source)
+
+      expected_offenses.zip(cop.offenses).each do |expected, actual|
+        expect_offense(expected, actual)
+      end
+    end
   end
   def expect_offense(expected, actual)
     expect(actual.message).to eq(expected[:message])