diff --git a/railties/lib/rails/test_unit/line_filtering.rb b/railties/lib/rails/test_unit/line_filtering.rb
index dab4d3631d0..b7635c71f4b 100644
--- a/railties/lib/rails/test_unit/line_filtering.rb
+++ b/railties/lib/rails/test_unit/line_filtering.rb
@@ -26,7 +26,7 @@ module Rails
     private
       def derive_regexp(filter)
         # Regexp filtering copied from Minitest.
-        filter =~ %r%/(.*)/% ? Regexp.new($1) : filter
+        Regexp.new $1 if filter =~ %r%/(.*)/%
       end
 
       def derive_line_filters(patterns)
diff --git a/railties/test/application/test_runner_test.rb b/railties/test/application/test_runner_test.rb
index a7eb0feb111..821ac9b0334 100644
--- a/railties/test/application/test_runner_test.rb
+++ b/railties/test/application/test_runner_test.rb
@@ -363,7 +363,7 @@ module ApplicationTests
         end
       RUBY
 
-      run_test_command('test/models/account_test.rb:4:9  test/models/post_test:4:9').tap do |output|
+      run_test_command('test/models/account_test.rb:4:9 test/models/post_test.rb:4:9').tap do |output|
         assert_match 'AccountTest:FirstFilter', output
         assert_match 'AccountTest:SecondFilter', output
         assert_match 'PostTest:FirstFilter', output
@@ -382,6 +382,30 @@ module ApplicationTests
       end
     end
 
+    def test_line_filters_trigger_only_one_runnable
+      app_file 'test/models/post_test.rb', <<-RUBY
+        require 'test_helper'
+
+        class PostTest < ActiveSupport::TestCase
+          test 'truth' do
+            assert true
+          end
+        end
+
+        class SecondPostTest < ActiveSupport::TestCase
+          test 'truth' do
+            assert false, 'ran second runnable'
+          end
+        end
+      RUBY
+
+      # Pass seed guaranteeing failure.
+      run_test_command('test/models/post_test.rb:4 --seed 30410').tap do |output|
+        assert_no_match 'ran second runnable', output
+        assert_match '1 runs, 1 assertions', output
+      end
+    end
+
     def test_shows_filtered_backtrace_by_default
       create_backtrace_test