Unable to install socket.io with npm on Centos 6.4

I'm trying to install socket.io via npm on a fresh Centos 6.4 (on a virtual machine). (yes running as root - just using this VM for testing purposes)

[root@localhost lib]# npm cache clean
[root@localhost lib]# npm install socket.io
npm http GET https://registry.npmjs.org/socket.io
npm http 200 https://registry.npmjs.org/socket.io
npm http GET https://registry.npmjs.org/socket.io/-/socket.io-0.9.14.tgz
npm http 200 https://registry.npmjs.org/socket.io/-/socket.io-0.9.14.tgz
npm http GET https://registry.npmjs.org/socket.io-client/0.9.11
npm http GET https://registry.npmjs.org/base64id/0.1.0
npm http GET https://registry.npmjs.org/policyfile/0.0.4
npm http GET https://registry.npmjs.org/redis/0.7.3
npm http 200 https://registry.npmjs.org/base64id/0.1.0
npm http 200 https://registry.npmjs.org/policyfile/0.0.4
npm http GET https://registry.npmjs.org/base64id/-/base64id-0.1.0.tgz
npm http GET https://registry.npmjs.org/policyfile/-/policyfile-0.0.4.tgz
npm http 200 https://registry.npmjs.org/socket.io-client/0.9.11
npm http GET https://registry.npmjs.org/socket.io-client/-/socket.io-client-0.9.11.tgz
npm http 200 https://registry.npmjs.org/redis/0.7.3
npm http GET https://registry.npmjs.org/redis/-/redis-0.7.3.tgz
npm http 200 https://registry.npmjs.org/policyfile/-/policyfile-0.0.4.tgz
npm http 200 https://registry.npmjs.org/base64id/-/base64id-0.1.0.tgz
npm http 200 https://registry.npmjs.org/socket.io-client/-/socket.io-client-0.9.11.tgz
npm http 200 https://registry.npmjs.org/redis/-/redis-0.7.3.tgz
npm http GET https://registry.npmjs.org/uglify-js/1.2.5
npm http GET https://registry.npmjs.org/ws
npm http GET https://registry.npmjs.org/active-x-obfuscator/0.0.1
npm http GET https://registry.npmjs.org/xmlhttprequest/1.4.2
npm http 200 https://registry.npmjs.org/active-x-obfuscator/0.0.1
npm http 200 https://registry.npmjs.org/uglify-js/1.2.5
npm http GET https://registry.npmjs.org/active-x-obfuscator/-/active-x-obfuscator-0.0.1.tgz
npm http GET https://registry.npmjs.org/uglify-js/-/uglify-js-1.2.5.tgz
npm http 200 https://registry.npmjs.org/xmlhttprequest/1.4.2
npm http GET https://registry.npmjs.org/xmlhttprequest/-/xmlhttprequest-1.4.2.tgz
npm http 200 https://registry.npmjs.org/ws
npm http GET https://registry.npmjs.org/ws/-/ws-0.4.25.tgz
npm http 200 https://registry.npmjs.org/active-x-obfuscator/-/active-x-obfuscator-0.0.1.tgz
npm http 200 https://registry.npmjs.org/uglify-js/-/uglify-js-1.2.5.tgz
npm http 200 https://registry.npmjs.org/xmlhttprequest/-/xmlhttprequest-1.4.2.tgz
npm http 200 https://registry.npmjs.org/ws/-/ws-0.4.25.tgz
npm http GET https://registry.npmjs.org/zeparser/0.0.5
npm http GET https://registry.npmjs.org/commander
npm http GET https://registry.npmjs.org/tinycolor
npm http GET https://registry.npmjs.org/options
npm http 200 https://registry.npmjs.org/zeparser/0.0.5
npm http GET https://registry.npmjs.org/zeparser/-/zeparser-0.0.5.tgz
npm http 200 https://registry.npmjs.org/options
npm http 200 https://registry.npmjs.org/tinycolor
npm http GET https://registry.npmjs.org/options/-/options-0.0.5.tgz
npm http GET https://registry.npmjs.org/tinycolor/-/tinycolor-0.0.1.tgz
npm http 200 https://registry.npmjs.org/zeparser/-/zeparser-0.0.5.tgz
npm http 200 https://registry.npmjs.org/commander
npm http GET https://registry.npmjs.org/commander/-/commander-0.6.1.tgz
npm http 200 https://registry.npmjs.org/options/-/options-0.0.5.tgz
npm http 200 https://registry.npmjs.org/tinycolor/-/tinycolor-0.0.1.tgz
npm http 200 https://registry.npmjs.org/commander/-/commander-0.6.1.tgz

> ws@0.4.25 install /lib/node_modules/socket.io/node_modules/socket.io-client/node_modules/ws
> (node-gyp rebuild 2> builderror.log) || (exit 0)

make: Entering directory `/lib/node_modules/socket.io/node_modules/socket.io-client/node_modules/ws/build'
  CXX(target) Release/obj.target/bufferutil/src/bufferutil.o
  SOLINK_MODULE(target) Release/obj.target/bufferutil.node
  SOLINK_MODULE(target) Release/obj.target/bufferutil.node: Finished
  COPY Release/bufferutil.node
  CXX(target) Release/obj.target/validation/src/validation.o
  SOLINK_MODULE(target) Release/obj.target/validation.node
  SOLINK_MODULE(target) Release/obj.target/validation.node: Finished
  COPY Release/validation.node
make: Leaving directory `/lib/node_modules/socket.io/node_modules/socket.io-client/node_modules/ws/build'
socket.io@0.9.14 node_modules/socket.io
├── base64id@0.1.0
├── policyfile@0.0.4
├── redis@0.7.3
└── socket.io-client@0.9.11 (xmlhttprequest@1.4.2, uglify-js@1.2.5, ws@0.4.25, active-x-obfuscator@0.0.1)
[root@localhost lib]# 

Checking this builderror.log file shows me it's totally empty.

[root@localhost lib]# cat /lib/node_modules/socket.io/node_modules/socket.io-client/node_modules/ws/builderror.log 
[root@localhost lib]# 

and

npm ls -g

Tells me there is no socket.io module installed on my system.

Thanks for your help!