diff --git a/definitions/grib2/local/ecmf/section4_extras.def b/definitions/grib2/local/ecmf/section4_extras.def
index 11cec8f50..e64ab0f48 100644
--- a/definitions/grib2/local/ecmf/section4_extras.def
+++ b/definitions/grib2/local/ecmf/section4_extras.def
@@ -1,14 +1,12 @@
 # (C) Copyright 2005- ECMWF.
 
-constant modelNameDefault = "unknown";
-constant modelVersionDefault = "unknown";
-
+# See ECC-1846
 if (centre is "ecmf" or datasetForLocal is "era6") {
- concept_nofail modelName (modelNameDefault, "modelNameConcept.def",conceptsMasterDir,conceptsLocalDirAll): no_copy, dump;
+ concept_nofail modelName (unknown, "modelNameConcept.def",conceptsMasterDir,conceptsLocalDirAll): no_copy, dump;
 
  if (!(modelName is "unknown")) {
-    concept_nofail modelVersion (modelVersionDefault, "modelVersionConcept_[modelName].def",conceptsMasterDir,conceptsLocalDirAll): no_copy, dump;
-    alias ls.model = modelName;
-    alias mars.model = modelName;
+    concept_nofail modelVersion (unknown, "modelVersionConcept_[modelName].def",conceptsMasterDir,conceptsLocalDirAll): no_copy, dump;
+    # alias ls.model = modelName;
+    # alias mars.model = modelName;
  }
 }