diff --git a/guacamole-common-js/src/main/resources/keyboard.js b/guacamole-common-js/src/main/resources/keyboard.js
index 4f957164f..fe2e777b3 100644
--- a/guacamole-common-js/src/main/resources/keyboard.js
+++ b/guacamole-common-js/src/main/resources/keyboard.js
@@ -444,7 +444,6 @@ Guacamole.Keyboard = function(element) {
         if (keydown_keysym)
             e.preventDefault();
         
-
         // Also try to get get keysym from keyIdentifier
         if (e.keyIdentifier) {
 
@@ -479,6 +478,8 @@ Guacamole.Keyboard = function(element) {
         // Only intercept if handler set
         if (!guac_keyboard.onkeydown) return;
 
+        e.preventDefault();
+
         var keynum;
         if (window.event) keynum = window.event.keyCode;
         else if (e.which) keynum = e.which;