diff --git a/lib/fog/core/collection.rb b/lib/fog/core/collection.rb
index 9f3658cf0..640648224 100644
--- a/lib/fog/core/collection.rb
+++ b/lib/fog/core/collection.rb
@@ -113,6 +113,7 @@ module Fog
     end
 
     def to_json
+      require 'json'
       self.map {|member| member.attributes}.to_json
     end
 
diff --git a/lib/fog/core/model.rb b/lib/fog/core/model.rb
index bc3213de8..c1bfb441e 100644
--- a/lib/fog/core/model.rb
+++ b/lib/fog/core/model.rb
@@ -33,6 +33,7 @@ module Fog
     end
 
     def to_json
+      require 'json'
       attributes.to_json
     end