diff --git a/src/world/generator/normal/Normal.php b/src/world/generator/normal/Normal.php
index 5c3db1729..be7de0765 100644
--- a/src/world/generator/normal/Normal.php
+++ b/src/world/generator/normal/Normal.php
@@ -95,12 +95,9 @@ class Normal extends Generator{
 						return BiomeIds::BIRCH_FOREST;
 					}
 				}else{
-					//FIXME: This will always cause River to be used since the rainfall is always greater than 0.8 if we
-					//reached this branch. However I don't think that substituting temperature for rainfall is correct given
-					//that mountain biomes are supposed to be pretty cold.
-					if($rainfall < 0.25){
+					if($temperature < 0.20){
 						return BiomeIds::MOUNTAINS;
-					}elseif($rainfall < 0.70){
+					}elseif($temperature < 0.40){
 						return BiomeIds::SMALL_MOUNTAINS;
 					}else{
 						return BiomeIds::RIVER;