diff --git a/lib4sbom/data/package.py b/lib4sbom/data/package.py
index 53dd59a..fd93ca0 100644
--- a/lib4sbom/data/package.py
+++ b/lib4sbom/data/package.py
@@ -74,6 +74,8 @@ def _validate_supplier_type(self, type):
             return supplier_type.capitalize()
         if supplier_type == "author":
             return "Person"
+        if supplier_type == "unknown":
+            return "UNKNOWN"
         return "Organization"
 
     def set_supplier(self, type, name):