diff --git a/Tests/varLib/varLib_test.py b/Tests/varLib/varLib_test.py
index 7e2a1411c..47137f1b3 100644
--- a/Tests/varLib/varLib_test.py
+++ b/Tests/varLib/varLib_test.py
@@ -2,14 +2,17 @@ from __future__ import print_function, division, absolute_import
 from fontTools.misc.py23 import *
 from fontTools.ttLib import TTFont
 from fontTools.varLib import build
-from fontTools.varLib import main as varLib_main
-from fontTools.designspaceLib import DesignSpaceDocumentError, DesignSpaceDocument
+from fontTools.varLib import main as varLib_main, load_masters
+from fontTools.designspaceLib import (
+    DesignSpaceDocumentError, DesignSpaceDocument, SourceDescriptor,
+)
 import difflib
 import os
 import shutil
 import sys
 import tempfile
 import unittest
+import pytest
 
 
 def reload_font(font):
@@ -308,5 +311,19 @@ class BuildTest(unittest.TestCase):
         self.expect_ttx(varfont, expected_ttx_path, tables)
 
 
+def test_load_masters_layerName_without_required_font():
+    ds = DesignSpaceDocument()
+    s = SourceDescriptor()
+    s.font = None
+    s.layerName = "Medium"
+    ds.addSource(s)
+
+    with pytest.raises(
+        AttributeError,
+        match="specified a layer name but lacks the required TTFont object",
+    ):
+        load_masters(ds)
+
+
 if __name__ == "__main__":
     sys.exit(unittest.main())