diff --git a/lib/readline.js b/lib/readline.js
index dc1cf977a38c3c..2cdd2cf392c71f 100644
--- a/lib/readline.js
+++ b/lib/readline.js
@@ -47,9 +47,7 @@ function Interface(input, output, completer, terminal) {
   }
   historySize = historySize || kHistorySize;
 
-  completer = completer || undefined;
-
-  if (typeof completer !== 'function' && typeof completer !== 'undefined') {
+  if (completer && typeof completer !== 'function') {
     throw new TypeError('Argument \'completer\' must be a function');
   }