diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 9a23bf0c7..1982654c4 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -1085,7 +1085,10 @@ The function of `param2` is determined by `paramtype2` in node definition.
     * Values range 0 - 23
     * facedir / 4 = axis direction:
       0 = y+,   1 = z+,   2 = z-,   3 = x+,   4 = x-,   5 = y-
-    * facedir modulo 4 = rotation around that axis
+    * The node is rotated 90 degrees around the X or Z axis so that its top face
+      points in the desired direction. For the y- direction, it's rotated 180
+      degrees around the Z axis.
+    * facedir modulo 4 = left-handed rotation around the specified axis, in 90° steps.
     * By default, on placement the param2 is automatically set to the
       horizondal direction the player was looking at (values 0-3)
     * Special case: If the node is a connected nodebox, the nodebox