diff --git a/toolkit/content/widgets/tree.xml b/toolkit/content/widgets/tree.xml
index e01ea443fd6..bee961c6594 100644
--- a/toolkit/content/widgets/tree.xml
+++ b/toolkit/content/widgets/tree.xml
@@ -484,7 +484,7 @@
       <handler event="keypress">
         <![CDATA[
          var c = this.currentIndex;
-         if (event.keyCode == ' '.charCodeAt(0)) {
+         if (event.charCode == ' '.charCodeAt(0)) {
            if (!this.view.selection.isSelected(c))
              this.view.selection.toggleSelect(c);
          }
diff --git a/xpfe/global/resources/content/bindings/tree.xml b/xpfe/global/resources/content/bindings/tree.xml
index 0ed533b684e..a8b53659709 100644
--- a/xpfe/global/resources/content/bindings/tree.xml
+++ b/xpfe/global/resources/content/bindings/tree.xml
@@ -477,7 +477,7 @@
       <handler event="keypress">
         <![CDATA[
          var c = this.currentIndex;
-         if (event.keyCode == ' '.charCodeAt(0)) {
+         if (event.charCode == ' '.charCodeAt(0)) {
            if (!this.view.selection.isSelected(c))
              this.view.selection.toggleSelect(c);
          }