diff --git a/lib/wmbus_decoder.js b/lib/wmbus_decoder.js
index 8022c7a..c660137 100644
--- a/lib/wmbus_decoder.js
+++ b/lib/wmbus_decoder.js
@@ -1282,7 +1282,7 @@ class WMBUS_DECODER {
         this.link_layer.afield_version = data[i++];
         this.link_layer.afield_type = data[i++];
 
-        this.link_layer.manufacturer = this.manId2ascii(this.link_layer.mfield);
+        this.link_layer.manufacturer = this.manId2ascii(this.link_layer.mfield).toUpperCase();
         this.link_layer.typestring = this.validDeviceTypes[this.link_layer.afield_type] || 'unknown';
         this.link_layer.afield_id = this.decodeBCD(8, this.link_layer.afield_raw).toString().padStart(8, '0');