diff --git a/lib/packer-build.js b/lib/packer-build.js
index <HASH>..<HASH> 100644
--- a/lib/packer-build.js
+++ b/lib/packer-build.js
@@ -50,7 +50,7 @@ function build(cfg) {
 
     pkg._nativeDependencies = cfg.packed.nativeDependencies;
 
-    cfg.zipname = moduleid + '-commonjs-' + version + '.zip';
+    cfg.zipname = (moduleid + '-commonjs-' + version + '.zip').toLowerCase();
     cfg.internalPath = 'modules/commonjs/' + moduleid + '/' + version;
 
     var zip = new AdmZip();
Zipfiles must have lower case names, fixes #<I>