diff --git a/notebook/tests/util.js b/notebook/tests/util.js
index 950cbcbc7..8a15b1d56 100644
--- a/notebook/tests/util.js
+++ b/notebook/tests/util.js
@@ -170,7 +170,7 @@ casper.wait_for_output = function (cell_num, out_num) {
         function then() { },
         function timeout() {
             this.echo("wait_for_output timed out on cell "+cell_num+", waiting for "+out_num+"outputs .");
-            pn = this.evaluate(function get_prompt(c) {
+            var pn = this.evaluate(function get_prompt(c) {
                 return IPython.notebook.get_cell(c).input_prompt_number;
             });
             this.echo("cell prompt was :'"+pn+"'.")