diff --git a/src/pEp/_pEp/message.cc b/src/pEp/_pEp/message.cc
index 11bd51a..3666669 100644
--- a/src/pEp/_pEp/message.cc
+++ b/src/pEp/_pEp/message.cc
@@ -95,7 +95,8 @@ namespace pEp {
         }
 
         object Message::Blob::data() {
-            return object(handle<>(PyBytes_FromString(_bl->value)));
+	  return object(handle<>(PyBytes_FromStringAndSize(_bl->value,
+							   _bl->size)));
         }
 
         void Message::Blob::data(object data) {
diff --git a/tests/test_blob.py b/tests/test_blob.py
index 857c369..b4df272 100644
--- a/tests/test_blob.py
+++ b/tests/test_blob.py
@@ -4,18 +4,28 @@
 
 """Blob unit tests."""
 
-import pytest
 
-from . import constants
-from . import model
-
-def test_blob_data_constructor(pEp, model):
-    bdata = bytes('this is test data', 'utf-8')
+def test_blob_data_constructor(pEp):
+    bdata = b'this is binary \x00\x01\xbb\xa7\xa4\xab test data'
     b = pEp.Blob(bdata)
-    assert(b.data == bdata)
+    assert b.data == bdata
+    assert not b.mime_type
+    assert not b.filename
+
 
-def test_blob_data_property(pEp, model):
+def test_blob_data_property(pEp):
+    bdata = b'this is binary \x00\x01\xbb\xa7\xa4\xab test data'
     b = pEp.Blob(b'dummy')
-    bdata = bytes('this is test data', 'utf-8')
     b.data = bdata
-    assert(b.data == bdata)
+    assert b.data == bdata
+    assert not b.mime_type
+    assert not b.filename
+
+
+def test_blob_data_property_keeps_other_fields(pEp):
+    bdata = b'this is binary \x00\x01\xbb\xa7\xa4\xab test data'
+    b = pEp.Blob(b'dummy', 'application/x-mydata', 'myfile.dat')
+    b.data = bdata
+    assert b.data == bdata
+    assert b.mime_type == 'application/x-mydata'
+    assert b.filename == 'myfile.dat'