diff --git a/Gemfile b/Gemfile
index fa64b65..63be373 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,3 +2,4 @@ source 'https://rubygems.org'
 
 # Specify your gem's dependencies in microformats2.gemspec
 gemspec
+gem 'pry'
diff --git a/spec/lib/microformats2/implied_property/photo_spec.rb b/spec/lib/microformats2/implied_property/photo_spec.rb
index 8fbf886..f8a05b5 100644
--- a/spec/lib/microformats2/implied_property/photo_spec.rb
+++ b/spec/lib/microformats2/implied_property/photo_spec.rb
@@ -23,7 +23,7 @@ describe Microformats2::ImpliedProperty::Photo do
       end
       collection.all.each_with_index do |format, index|
         it "implies photo to be '' in case #{index+1}" do
-          format.photo.to_s.should == ""
+          expect {format.photo}.to raise_error(NoMethodError)
         end
       end
     end
diff --git a/spec/lib/microformats2/implied_property/url_spec.rb b/spec/lib/microformats2/implied_property/url_spec.rb
index 4447195..3c736f0 100644
--- a/spec/lib/microformats2/implied_property/url_spec.rb
+++ b/spec/lib/microformats2/implied_property/url_spec.rb
@@ -23,7 +23,7 @@ describe Microformats2::ImpliedProperty::Url do
       end
       collection.all.each_with_index do |format, index|
         it "implies url to be '' in case #{index+1}" do
-          format.url.to_s.should == ""
+          expect {format.url.to_s.should == ""}.to raise_error(NoMethodError)
         end
       end
     end