diff --git a/doc/YAOM.md b/doc/YAOM.md
index 3953d5c..b42b85b 100644
--- a/doc/YAOM.md
+++ b/doc/YAOM.md
@@ -85,7 +85,7 @@ The coordinate system used is **WGS84**.
 The individual datasets and the planet file are distributed as **PBF** files.
 
 ### Numbering
-In order to merge all the datasets into one coherent database, unique ID's are required. The merge script takes care of it before merging all datasets.
+In order to merge all the datasets into one coherent database, unique IDs are required. The merge script takes care of it before merging all datasets.
 
 All ID's on YAOM can change. Future versions of this specification could make mandatory for features to have a permanent and unique ID that could be linked to.