3 files changed, 7 insertions, 1 deletions
diff --git a/string.c b/string.c
index ab798065d1..221d50eedf 100644
--- a/string.c
+++ b/string.c
@@ -3969,6 +3969,7 @@ str_succ(VALUE str)
             }
             carry_pos = s - sbeg;
 	}
+	ENC_CODERANGE_SET(str, ENC_CODERANGE_UNKNOWN);
     }
     RESIZE_CAPA(str, slen + carry_len);
     sbeg = RSTRING_PTR(str);
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 2c18229511..191d5fc705 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -1660,6 +1660,11 @@ CODE
 
     assert_equal("!", " ".succ)
     assert_equal("", "".succ)
+
+    bug = '[ruby-core:83062] [Bug #13952]'
+    s = "\xff".b
+    assert_not_predicate(s, :ascii_only?)
+    assert_predicate(s.succ, :ascii_only?, bug)
   end
 
   def test_succ!
diff --git a/version.h b/version.h
index 4c4aa0e523..d0e510661a 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.4.4"
 #define RUBY_RELEASE_DATE "2017-12-25"
-#define RUBY_PATCHLEVEL 225
+#define RUBY_PATCHLEVEL 226
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 12