diff --git a/lib/namespace.js b/lib/namespace.js
index 6d0ac17065..bca8a3e99f 100644
--- a/lib/namespace.js
+++ b/lib/namespace.js
@@ -262,6 +262,9 @@ Namespace.prototype.write = function(){
  */
 
 Namespace.prototype.clients = function(fn){
+  if(!this.adapter){
+    throw new Error('No adapter for this namespace, are you trying to get the list of clients of a dynamic namespace?')
+  }
   this.adapter.clients(this.rooms, fn);
   // reset rooms for scenario:
   // .in('room').clients() (GH-1978)