diff --git a/ChangeLog b/ChangeLog
index 73f95af7eb..157d98f21b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jan 18 12:04:34 2016  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* test/ruby/test_string.rb: Added extra testcase for test_rstrip_bang
+	  and test_lstrip_bang. [fix GH-1178] Patch by @Matrixbirds
+
 Mon Jan 18 11:47:27 2016  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
 
 	* string.c: fix a typo. [fix GH-1202][ci skip] Patch by @sunboshan
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 0120bff9bd..7eed784c8a 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2155,6 +2155,10 @@ class TestString < Test::Unit::TestCase
     assert_equal(nil, s3.rstrip!)
     assert_equal("  \u3042", s3)
 
+    s4 = S("\u3042")
+    assert_equal(nil, s4.rstrip!)
+    assert_equal("\u3042", s4)
+
     assert_raise(Encoding::CompatibilityError) { "\u3042".encode("ISO-2022-JP").rstrip! }
   end
 
@@ -2175,6 +2179,10 @@ class TestString < Test::Unit::TestCase
     s3 = S("  \u3042")
     assert_equal("\u3042", s3.lstrip!)
     assert_equal("\u3042", s3)
+
+    s4 = S("\u3042")
+    assert_equal(nil, s4.lstrip!)
+    assert_equal("\u3042", s4)
   end
 
 =begin