diff --git a/wagtail/core/signals.py b/wagtail/core/signals.py
index 44d6fedb30..3ce67b215a 100644
--- a/wagtail/core/signals.py
+++ b/wagtail/core/signals.py
@@ -5,12 +5,12 @@ page_unpublished = Signal(providing_args=['instance'])
 pre_page_move = Signal(providing_args=['instance', 'parent_page_before', 'parent_page_after', 'url_path_before', 'url_path_after'])
 post_page_move = Signal(providing_args=['instance', 'parent_page_before', 'parent_page_after', 'url_path_before', 'url_path_after'])
 
-workflow_approved = Signal(providing_args=['instance'])
-workflow_rejected = Signal(providing_args=['instance'])
-workflow_cancelled = Signal(providing_args=['instance'])
-workflow_submitted = Signal(providing_args=['instance'])
+workflow_approved = Signal(providing_args=['instance', 'user'])
+workflow_rejected = Signal(providing_args=['instance', 'user'])
+workflow_cancelled = Signal(providing_args=['instance', 'user'])
+workflow_submitted = Signal(providing_args=['instance', 'user'])
 
-task_approved = Signal(providing_args=['instance'])
-task_rejected = Signal(providing_args=['instance'])
-task_submitted = Signal(providing_args=['instance'])
-task_cancelled = Signal(providing_args=['instance'])
+task_approved = Signal(providing_args=['instance', 'user'])
+task_rejected = Signal(providing_args=['instance', 'user'])
+task_submitted = Signal(providing_args=['instance', 'user'])
+task_cancelled = Signal(providing_args=['instance' 'user'])