diff --git a/lib/core.js b/lib/core.js
index 4e32332b..fac0b452 100644
--- a/lib/core.js
+++ b/lib/core.js
@@ -193,7 +193,9 @@ SystemJSLoader.prototype.config = function(cfg) {
 
   if (cfg.packages) {
     for (var p in cfg.packages) {
-      var prop = this.normalizeSync(p);
+      // request with trailing "/" to get package name exactly
+      var prop = this.normalizeSync(p + '/');
+      prop = prop.substr(0, prop.length - 1);
 
       // if doing default js extensions, undo to get package name
       if (this.defaultJSExtensions && p.substr(p.length - 3, 3) != '.js')
diff --git a/lib/package.js b/lib/package.js
index 19af9282..2342dd54 100644
--- a/lib/package.js
+++ b/lib/package.js
@@ -181,6 +181,10 @@
     if (normalized.length == pkgName.length)
       return normalized + defaultExtension;
 
+    // allow for direct package name normalization with trailling "/" (no main)
+    if (normalized.length == pkgName.length + 1 && normalized[pkgName.length] == '/')
+      return normalized;
+
     // sync normalize does not apply package map
     if (sync || !pkg.map)
       return pkgName + '/' + basePath + normalized.substr(pkgName.length + 1) + defaultExtension;