diff --git a/Gemfile b/Gemfile
index e5a11cc..97b9b70 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gemspec
 
 platforms :mingw_19, :ruby_19 do
-  gem 'json', '~> 1.8'
+  gem 'json', '~> 2.0'
 end
 
 group :benchmarking do
diff --git a/lib/oga/xpath/conversion.rb b/lib/oga/xpath/conversion.rb
index e9b6b27..2727716 100644
--- a/lib/oga/xpath/conversion.rb
+++ b/lib/oga/xpath/conversion.rb
@@ -76,7 +76,7 @@ module Oga
 
         if value.is_a?(Float)
           bool = !value.nan? && !value.zero?
-        elsif value.is_a?(Fixnum)
+        elsif value.is_a?(Integer)
           bool = !value.zero?
         elsif value.respond_to?(:empty?)
           bool = !value.empty?