diff --git a/VERSION b/VERSION
index 227cea2..7ec1d6d 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.0.0
+2.1.0
diff --git a/dependencyci.yml b/dependencyci.yml
new file mode 100644
index 0000000..0c67c1b
--- /dev/null
+++ b/dependencyci.yml
@@ -0,0 +1,5 @@
+platform:
+  Rubygems:
+    rdf-isomorphic:
+      tests:
+        unmaintained: skip
\ No newline at end of file
diff --git a/lib/rdf/spec/enumerable.rb b/lib/rdf/spec/enumerable.rb
index b98eb37..4cf0d37 100644
--- a/lib/rdf/spec/enumerable.rb
+++ b/lib/rdf/spec/enumerable.rb
@@ -512,11 +512,23 @@
 
 
   context "when converting" do
-    it {is_expected.to respond_to(:to_hash)}
-    its(:to_hash) {is_expected.to be_instance_of(Hash)}
-    context "#to_hash" do
+    it {is_expected.to respond_to(:to_h)}
+    it {is_expected.not_to respond_to(:to_hash)}
+    its(:to_hash) {
+      expect {
+        is_expected.to be_instance_of(Hash)
+      }.to write("DEPRECATION").to(:error)
+    }
+    describe "#to_h" do
       it "should have as many keys as subjects" do
-        expect(subject.to_hash.keys.size).to eq enumerable.subjects.to_a.size
+        expect(subject.to_h.keys.size).to eq enumerable.subjects.to_a.size
+      end
+    end
+    describe "#to_h" do
+      it "should have as many keys as subjects (with deprecation)" do
+        expect {
+          expect(subject.to_hash.keys.size).to eq enumerable.subjects.to_a.size
+        }.to write("DEPRECATION").to(:error)
       end
     end
   end
diff --git a/lib/rdf/spec/mutable.rb b/lib/rdf/spec/mutable.rb
index 72d38d7..1611a73 100644
--- a/lib/rdf/spec/mutable.rb
+++ b/lib/rdf/spec/mutable.rb
@@ -262,7 +262,7 @@
         it 'handles Graph names' do
           if @supports_named_graphs
             dels = non_bnode_statements.take(10).map do |st|
-              RDF::Statement.from(st.to_hash.merge(graph_name: RDF::URI('http://example.com/fake')))
+              RDF::Statement.from(st.to_h.merge(graph_name: RDF::URI('http://example.com/fake')))
             end
             dels.map! { |st| st.graph_name = RDF::URI('http://example.com/fake'); st }
             dels.extend(RDF::Enumerable)
diff --git a/lib/rdf/spec/writable.rb b/lib/rdf/spec/writable.rb
index fc3c6f5..f111dc1 100644
--- a/lib/rdf/spec/writable.rb
+++ b/lib/rdf/spec/writable.rb
@@ -126,9 +126,9 @@
     end
 
     it "should not insert an incomplete statement" do
-      expect {subject.insert(RDF::Statement.from(statement.to_hash.merge(subject: nil)))}.to raise_error(ArgumentError)
-      expect {subject.insert(RDF::Statement.from(statement.to_hash.merge(predicate: nil)))}.to raise_error(ArgumentError)
-      expect {subject.insert(RDF::Statement.from(statement.to_hash.merge(object: nil)))}.to raise_error(ArgumentError)
+      expect {subject.insert(RDF::Statement.from(statement.to_h.merge(subject: nil)))}.to raise_error(ArgumentError)
+      expect {subject.insert(RDF::Statement.from(statement.to_h.merge(predicate: nil)))}.to raise_error(ArgumentError)
+      expect {subject.insert(RDF::Statement.from(statement.to_h.merge(object: nil)))}.to raise_error(ArgumentError)
       expect(subject.count).to eql 0
     end