diff --git a/lib/helpers/normalizeArgs.js b/lib/helpers/normalizeArgs.js
index a7e44d1..f5650b5 100644
--- a/lib/helpers/normalizeArgs.js
+++ b/lib/helpers/normalizeArgs.js
@@ -16,7 +16,10 @@ function normalizeArgs(registry, args) {
     return fn;
   }
 
-  return map(flatten(args), getFunction);
+  var flattenArgs = flatten(args);
+  assert(flattenArgs.length, 'Arguments must be a non-empty array or string');
+
+  return map(flattenArgs, getFunction);
 }
 
 module.exports = normalizeArgs;