diff --git a/lib/rdf/spec/repository.rb b/lib/rdf/spec/repository.rb
index ba379f1..c6b2f63 100644
--- a/lib/rdf/spec/repository.rb
+++ b/lib/rdf/spec/repository.rb
@@ -38,7 +38,7 @@
     
     describe '#delete_insert' do
       it 'updates transactionally' do
-        if mutable.mutable?
+        if mutable.mutable? & mutable.supports?(:atomic_write)
           expect(mutable).to receive(:commit_transaction).and_call_original
           statement = RDF::Statement(:s, RDF::URI.new("urn:predicate:1"), :o)