diff --git a/test/plugin/test_filter_flowcounter_simple.rb b/test/plugin/test_filter_flowcounter_simple.rb
index a6fca59..0ab6942 100644
--- a/test/plugin/test_filter_flowcounter_simple.rb
+++ b/test/plugin/test_filter_flowcounter_simple.rb
@@ -26,7 +26,7 @@ def test_filter
     d = create_driver
     filtered, out = filter(d, msgs)
     assert_equal msgs, filtered
-    assert( out.include?("count:20"), out )
+    assert { out.include?("count:20") }
   end
 
   private
diff --git a/test/plugin/test_out_flowcounter_simple.rb b/test/plugin/test_out_flowcounter_simple.rb
index 03b75ab..07a158e 100644
--- a/test/plugin/test_out_flowcounter_simple.rb
+++ b/test/plugin/test_out_flowcounter_simple.rb
@@ -38,7 +38,7 @@ def test_num
       end
     end
     out = capture_log(d1.instance.log) { d1.instance.flush_emit(60) }
-    assert( out.include?("count:30"), out )
+    assert { out.include?("count:30") }
   end
 
   def test_byte
@@ -51,7 +51,7 @@ def test_byte
       end
     end
     out = capture_log(d1.instance.log) { d1.instance.flush_emit(60) }
-    assert( out =~ /count:\d+\tindicator:byte\tunit:second/, out )
+    assert { out =~ /count:\d+\tindicator:byte\tunit:second/ }
   end
 
   def test_comment
@@ -64,6 +64,6 @@ def test_comment
       end
     end
     out = capture_log(d1.instance.log) { d1.instance.flush_emit(60) }
-    assert( out.include?("comment:foobar"), out )
+    assert { out.include?("comment:foobar") }
   end
 end