1 files changed, 7 insertions, 1 deletions
diff --git a/ext/-test-/string/cstr.c b/ext/-test-/string/cstr.c
index d4ff360575..c2ed410b41 100644
--- a/ext/-test-/string/cstr.c
+++ b/ext/-test-/string/cstr.c
@@ -1,16 +1,22 @@
 #include "ruby.h"
+#include "ruby/encoding.h"
 
 static VALUE
 bug_str_cstr_term(VALUE str)
 {
     long len;
     char *s;
+    int c;
+    rb_encoding *enc;
+
     rb_str_modify(str);
     len = RSTRING_LEN(str);
     RSTRING_PTR(str)[len] = 'x';
     s = StringValueCStr(str);
     rb_gc();
-    return INT2NUM(s[len]);
+    enc = rb_enc_get(str);
+    c = rb_enc_codepoint(&s[len], &s[len+rb_enc_mbminlen(enc)], enc);
+    return INT2NUM(c);
 }
 
 void