diff --git a/string.c b/string.c
index 5e1769a792..bc625008ef 100644
--- a/string.c
+++ b/string.c
@@ -800,7 +800,7 @@ rb_enc_str_new_cstr(const char *ptr, rb_encoding *enc)
 }
 
 static VALUE
-str_new_static(VALUE klass, const char *ptr, long len, int encindex)
+str_new_with_buf(VALUE klass, const char *ptr, long len, int encindex)
 {
     VALUE str;
 
@@ -819,12 +819,23 @@ str_new_static(VALUE klass, const char *ptr, long len, int encindex)
 	RSTRING(str)->as.heap.ptr = (char *)ptr;
 	RSTRING(str)->as.heap.aux.capa = len;
 	STR_SET_NOEMBED(str);
-	RBASIC(str)->flags |= STR_NOFREE;
     }
     rb_enc_associate_index(str, encindex);
     return str;
 }
 
+static VALUE
+str_new_static(VALUE klass, const char *ptr, long len, int encindex)
+{
+    VALUE str = str_new_with_buf(klass, ptr, len, encindex);
+
+    if (ptr) {
+	RBASIC(str)->flags |= STR_NOFREE;
+    }
+
+    return str;
+}
+
 VALUE
 rb_str_new_static(const char *ptr, long len)
 {
@@ -850,6 +861,30 @@ rb_enc_str_new_static(const char *ptr, long len, rb_encoding *enc)
 }
 
 VALUE
+rb_str_new_with_buf(const char *ptr, long len)
+{
+    return str_new_with_buf(rb_cString, ptr, len, 0);
+}
+
+VALUE
+rb_usascii_str_new_with_buf(const char *ptr, long len)
+{
+    return str_new_with_buf(rb_cString, ptr, len, ENCINDEX_US_ASCII);
+}
+
+VALUE
+rb_utf8_str_new_with_buf(const char *ptr, long len)
+{
+    return str_new_with_buf(rb_cString, ptr, len, ENCINDEX_UTF_8);
+}
+
+VALUE
+rb_enc_str_new_with_buf(const char *ptr, long len, rb_encoding *enc)
+{
+    return str_new_with_buf(rb_cString, ptr, len, rb_enc_to_index(enc));
+}
+
+VALUE
 rb_tainted_str_new(const char *ptr, long len)
 {
     VALUE str = rb_str_new(ptr, len);