diff --git a/doc/lua_api.md b/doc/lua_api.md
index 07f70c36f..0034a79ab 100644
--- a/doc/lua_api.md
+++ b/doc/lua_api.md
@@ -6586,6 +6586,7 @@ Environment access
 * `core.get_value_noise(noiseparams)`
     * Return world-specific value noise.
     * The actual seed used is the noiseparams seed plus the world seed.
+    * **Warning**: Requires the mapgen enviorment to be initalized, do not use at load time.
 * `core.get_value_noise(seeddiff, octaves, persistence, spread)`
     * Deprecated: use `core.get_value_noise(noiseparams)` instead.
 * `core.get_perlin(noiseparams)`
@@ -9269,6 +9270,8 @@ It can be created via `ValueNoise()` or `core.get_value_noise()`.
 For `core.get_value_noise()`, the actual seed used is the noiseparams seed
 plus the world seed, to create world-specific noise.
 
+**Warning** These require the mapgen enviorment to be initalized, do not use at load time.
+
 * `ValueNoise(noiseparams)`
 * `ValueNoise(seed, octaves, persistence, spread)` (deprecated)
 * `core.get_value_noise(noiseparams)`
@@ -9305,6 +9308,8 @@ For each of the functions with an optional `buffer` parameter: If `buffer` is
 not nil, this table will be used to store the result instead of creating a new
 table.
 
+**Warning** These require the mapgen enviorment to be initalized, do not use at load time.
+
 ### Methods
 
 * `get_2d_map(pos)`: returns a `<size.x>` times `<size.y>` 2D array of 2D noise