diff --git a/README_API.md b/README_API.md
index 6040beb..d0b2bdd 100644
--- a/README_API.md
+++ b/README_API.md
@@ -149,6 +149,14 @@ Check if a Monarch screen is visible.
 * `exists` (boolean) - True if the screen is visible.
 
 
+## monarch.set_timestep_below_popup(screen_id, timestep)
+Set the timestep to apply for a screen when below a popup.
+
+**PARAMETERS**
+* `screen_id` (string|hash) - Id of the screen to change timestep setting for
+* `timestep` (number) - Timestep to apply
+
+
 ## monarch.add_listener([url])
 Add a URL that will be notified of navigation events.
 
diff --git a/monarch/monarch.lua b/monarch/monarch.lua
index 0b88888..c50a177 100644
--- a/monarch/monarch.lua
+++ b/monarch/monarch.lua
@@ -1155,6 +1155,19 @@ function M.bottom(offset)
 	return screen and screen.id
 end
 
+
+--- Set the timestep to apply for a screen when below a popup
+-- @param id (string|hash) Id of the screen to change timestep setting for
+-- @param timestep (number) Timestep to apply
+function M.set_timestep_below_popup(id, timestep)
+	assert(id, "You must provide a screen id")
+	assert(timestep, "You must provide a timestep")
+	id = tohash(id)
+	assert(screens[id], ("There is no screen registered with id %s"):format(tostring(id)))
+	screens[id].timestep_below_popup = timestep
+end
+
+
 local function url_to_key(url)
 	return (url.socket or hash("")) .. (url.path or hash("")) .. (url.fragment or hash(""))
 end