diff --git a/nrrd/tests/test_writing.py b/nrrd/tests/test_writing.py
index 161c23a..c05187b 100644
--- a/nrrd/tests/test_writing.py
+++ b/nrrd/tests/test_writing.py
@@ -184,21 +184,23 @@ def test_write_fake_encoding(self):
 
     def test_write_detached_raw(self):
         output_filename = os.path.join(self.temp_write_dir, 'testfile_detached_raw.nhdr')
-        output_data_filename = os.path.join(self.temp_write_dir, 'testfile_detached_raw.raw')
 
+        # Data & header are still detached even though detached_header is False because the filename is .nhdr
+        # Test also checks detached data filename that it is relative (default value)
         nrrd.write(output_filename, self.data_input, {u'encoding': 'raw'}, detached_header=False)
 
         # Read back the same file
         data, header = nrrd.read(output_filename)
         self.assertEqual(self.expected_data, data.tostring(order='F'))
         self.assertEqual(header['encoding'], 'raw')
-        self.assertEqual(header['data file'], output_data_filename)
+        self.assertEqual(header['data file'], 'testfile_detached_raw.raw')
 
     def test_write_detached_gz(self):
         output_filename = os.path.join(self.temp_write_dir, 'testfile_detached_raw.nhdr')
         output_data_filename = os.path.join(self.temp_write_dir, 'testfile_detached_raw.raw.gz')
 
         # Data & header are still detached even though detached_header is False because the filename is .nhdr
+        # Test also checks detached data filename that it is absolute
         nrrd.write(output_filename, self.data_input, {u'encoding': 'gz'}, detached_header=False,
                    relative_data_path=False)
 
@@ -212,6 +214,7 @@ def test_write_detached_bz2(self):
         output_filename = os.path.join(self.temp_write_dir, 'testfile_detached_raw.nhdr')
 
         # Data & header are still detached even though detached_header is False because the filename is .nhdr
+        # Test also checks detached data filename that it is relative (default value)
         nrrd.write(output_filename, self.data_input, {u'encoding': 'bz2'}, detached_header=False)
 
         # Read back the same file
@@ -224,6 +227,7 @@ def test_write_detached_ascii(self):
         output_filename = os.path.join(self.temp_write_dir, 'testfile_detached_raw.nhdr')
 
         # Data & header are still detached even though detached_header is False because the filename is .nhdr
+        # Test also checks detached data filename that it is relative (default value)
         nrrd.write(output_filename, self.data_input, {u'encoding': 'txt'}, detached_header=False)
 
         # Read back the same file