diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 276def259..52a7277fd 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -2604,6 +2604,7 @@ This is basically a reference to a C++ `ServerActiveObject`
         * `speed`: multiplier to default walking speed value (default: `1`)
         * `jump`: multiplier to default jump value (default: `1`)
         * `gravity`: multiplier to default gravity value (default: `1`)
+        * `slip` : multiplier to current walkable node groups slip value (default: `1`)
         * `sneak`: whether player can sneak (default: `true`)
         * `sneak_glitch`: whether player can use the sneak glitch (default: `true`)
 * `get_physics_override()`: returns the table given to set_physics_override