diff --git a/src/hdmf/testing/validate_spec.py b/src/hdmf/testing/validate_spec.py
index 89b8704bf..274d97978 100755
--- a/src/hdmf/testing/validate_spec.py
+++ b/src/hdmf/testing/validate_spec.py
@@ -32,7 +32,8 @@ def __init__(self):
     new_resolver = FixResolver()
 
     f_nwb = open(fpath_spec, 'r')
-    instance = yaml.safe_load(f_nwb)
+    yaml = YAML(typ='safe', pure=True)
+    instance = yaml.load(f_nwb)
 
     jsonschema.validate(instance, schema, resolver=new_resolver)