diff --git a/README.md b/README.md
index 5886092..47d83bb 100644
--- a/README.md
+++ b/README.md
@@ -222,7 +222,7 @@ ADD | MULTIPLY | MULTIPLY_ALL_MODIFIERS
 
 - [_<attribute>_](https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/attribute/Attribute.html) - A list of valid attributes
 - [_<equipment slot>_](https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/inventory/EquipmentSlot.html) - A list of valid equipment slots
-- _<world>_ - A string representation of world name (i.e. WORLD, WORLD_THE_END, etc.)
+- _<world>_ - A case-sensitive string representation of world name (i.e. world, world_nether, world_the_end, etc.)
 
 **trades.yml example**