1 files changed, 1 insertions, 0 deletions
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index 9d1b204eb7..f5fe2e3fa4 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -532,6 +532,7 @@ zstream_detach_buffer(z)
     z->buf_filled = 0;
     z->stream.next_out = 0;
     z->stream.avail_out = 0;
+    RBASIC(dst)->klass = rb_cString;
     return dst;
 }