diff --git a/lib/npm.js b/lib/npm.js
index 907b1a8..0842210 100644
--- a/lib/npm.js
+++ b/lib/npm.js
@@ -254,7 +254,7 @@ NPMLocation.prototype = {
 
     // warn if using jspm-style dependencies at this point
     for (var d in pjson.dependencies)
-      if (!pjson.dependencies[d].match(/^(https?|git)[:+]/) && pjson.dependencies[d].indexOf(':') > 0)
+      if (!pjson.dependencies[d].match(/^(https?|git)[:+]|(.)[:\/]/))
         throw 'Package.json dependency %' + d + '% set to `' + pjson.dependencies[d] + '`, which is not a valid dependency format for npm.'
           + '\nIt\'s advisable to publish jspm-style packages to GitHub or another `registry` so conventions are clear.';
           + '\nTo skip npm compatibility install with %jspm install ' + packageName + '-o "{jspmNodeConversion: false}"%.'