diff --git a/lib/galaxy/web/controllers/dataset.py b/lib/galaxy/web/controllers/dataset.py
index 8d3a2fab60d..a863b826f6b 100644
--- a/lib/galaxy/web/controllers/dataset.py
+++ b/lib/galaxy/web/controllers/dataset.py
@@ -316,6 +316,7 @@ class DatasetInterface( BaseController, UsesAnnotations, UsesHistory, UsesHistor
         
         valid_chars = '.,^_-()[]0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
         fname = ''.join(c in valid_chars and c or '_' for c in data.name)[0:150]
+        trans.response.headers["Content-Type"] = "application/octet-stream"
         trans.response.headers["Content-Disposition"] = "attachment; filename=Galaxy%s-[%s].%s" % (data.hid, fname, metadata_type)
         return open(data.metadata.get(metadata_type).file_name)