diff --git a/chrome/content/zotero/bindings/itembox.xml b/chrome/content/zotero/bindings/itembox.xml
index 11ffeacd0c..647f13eb83 100644
--- a/chrome/content/zotero/bindings/itembox.xml
+++ b/chrome/content/zotero/bindings/itembox.xml
@@ -1375,6 +1375,12 @@
 						this._dynamicFields.focus();
 					}
 					
+					// In Firefox 45, when clicking a multiline field such as Extra, the event is
+					// triggered on the inner 'description' element instead of the 'vbox'.
+					if (elem.tagName == 'description') {
+						elem = elem.parentNode;
+					}
+					
 					Zotero.debug('Showing editor');
 					
 					var fieldName = elem.getAttribute('fieldname');