diff --git a/ucs-school-umc-computerroom/umc/js/computerroom.js b/ucs-school-umc-computerroom/umc/js/computerroom.js
index d761393..2948de0 100644
--- a/ucs-school-umc-computerroom/umc/js/computerroom.js
+++ b/ucs-school-umc-computerroom/umc/js/computerroom.js
@@ -919,11 +919,6 @@ define([
 					return;
 				}
 
-				// stop the timer
-				if (this._examEndTimer) {
-					window.clearTimeout(this._examEndTimer);
-				}
-
 				// start collection the files
 				var info = this.get('roomInfo') || {};
 				var deferred = this.umcpCommand('schoolexam/exam/collect', {
@@ -968,6 +963,12 @@ define([
 					return;
 				}
 
+				// stop the timer
+				if (this._examEndTimer) {
+					window.clearTimeout(this._examEndTimer);
+					this._examEndTimer = null;
+				}
+
 				// start finishing the exam
 				var info = this.get('roomInfo') || {};
 				this.umcpCommand('schoolexam/exam/finish', {