1 files changed, 7 insertions, 4 deletions
diff --git a/string.c b/string.c
index 156d124e59..d0057b7d39 100644
--- a/string.c
+++ b/string.c
@@ -1506,10 +1506,13 @@ str_duplicate(VALUE klass, VALUE str)
     MEMCPY(RSTRING(dup)->as.ary, RSTRING(str)->as.ary,
 	   char, embed_size);
     if (flags & STR_NOEMBED) {
-	if (UNLIKELY(!(flags & FL_FREEZE))) {
-	    str = str_new_frozen(klass, str);
-	    FL_SET_RAW(str, flags & FL_TAINT);
-	    flags = FL_TEST_RAW(str, flag_mask);
+        if (FL_TEST_RAW(str, STR_SHARED)) {
+            str = RSTRING(str)->as.heap.aux.shared;
+        }
+        else if (UNLIKELY(!(flags & FL_FREEZE))) {
+            str = str_new_frozen(klass, str);
+            FL_SET_RAW(str, flags & FL_TAINT);
+            flags = FL_TEST_RAW(str, flag_mask);
 	}
 	if (flags & STR_NOEMBED) {
 	    RB_OBJ_WRITE(dup, &RSTRING(dup)->as.heap.aux.shared, str);