diff --git a/engine.lua b/engine.lua
index f42a214..303f7f7 100644
--- a/engine.lua
+++ b/engine.lua
@@ -23,6 +23,13 @@ if storage:contains("dig_penalty") then
     )
 end
 
+local speed_factor_storage = {}
+if storage:contains("speed_factor") then
+    speed_factor_storage = minetest.deserialize(
+        storage:get_string("speed_factor")
+    )
+end
+
 
 ---@param dig_penalty number
 local function set_dig_penalty(player, dig_penalty)
@@ -120,3 +127,33 @@ minetest.register_on_player_inventory_action(
     end
 )
 
+
+---@param speed_factor number
+local function set_speed(player, speed_factor)
+    local pname = player:get_player_name()
+    local prev_speed_factor = speed_factor_storage[pname] or 1
+    if speed_factor == prev_speed_factor then
+        return
+    end
+    if speed_factor < 0 then
+        speed_factor = prev_speed_factor
+    end
+    speed_factor_storage[pname] = speed_factor
+    storage:set_string(
+        "speed_factor",
+        minetest.serialize(
+            speed_factor_storage
+        )
+    )
+
+    player_monoids.speed:del_change(player, "medical")
+    player_monoids.speed:add_change(player, speed_factor, "medical")
+end
+
+
+minetest.register_on_joinplayer(
+    function(player, last_login)
+        set_speed(player, -1)
+    end
+)
+
diff --git a/mod.conf b/mod.conf
index 1cadb01..fb27a6e 100644
--- a/mod.conf
+++ b/mod.conf
@@ -1,3 +1,3 @@
 name = medical
 description = Health and nutrition
-depends = unified_inventory, toolcap_monoids, hand_monoid
\ No newline at end of file
+depends = unified_inventory, player_monoids, toolcap_monoids, hand_monoid
\ No newline at end of file