diff --git a/README.md b/README.md
index 625de37..6a257ee 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,10 @@ data that uses Google Protocol Buffers as low-level storage.
 
 For more information see https://wiki.openstreetmap.org/wiki/PBF_Format .
 
+Note that this is a low-level library that does only part of the
+encoding/decoding needed for actually writing/reading an OSM PBF file. For
+something more complete see [libosmium](https://osmcode.org/libosmium/).
+
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