--- a/README.md
+++ b/README.md
@@ -24,6 +24,9 @@
 
     ([name], [puid], [tool]*).
 
+The Pronom importer does not retrieve newer formats (Pronom IDs higher than about 450). So it might be necessary to run the kbgen,
+add required formats that are missing to the cache_pronom_formats.json file, and rerun the kbgen.
+
 
 Build
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