1 files changed, 1 insertions, 0 deletions
diff --git a/string.c b/string.c
index e1bd9a052e..0c782a430f 100644
--- a/string.c
+++ b/string.c
@@ -4079,6 +4079,7 @@ 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);