1 files changed, 4 insertions, 0 deletions
diff --git a/string.c b/string.c
index 3518cf5601..0efcf49b27 100644
--- a/string.c
+++ b/string.c
@@ -1363,6 +1363,7 @@ rb_str_resurrect(VALUE str)
  *  times (and call many realloc).
  */
 
+static inline void str_modifiable(VALUE str);
 static VALUE
 rb_str_init(int argc, VALUE *argv, VALUE str)
 {
@@ -1414,6 +1415,9 @@ rb_str_init(int argc, VALUE *argv, VALUE str)
     }
     else if (n == 1) {
 	StringValue(orig);
+	if (OBJ_FROZEN(str)) {
+	    rb_error_frozen_object(str);
+	}
 	str_replace(str, orig);
     }
     return str;