diff --git a/extensions/openpower-pels/fru_identity.cpp b/extensions/openpower-pels/fru_identity.cpp
index 63c81fb..8c81e88 100644
--- a/extensions/openpower-pels/fru_identity.cpp
+++ b/extensions/openpower-pels/fru_identity.cpp
@@ -88,7 +88,7 @@
     return std::nullopt;
 }
 
-void FRUIdentity::flatten(Stream& pel)
+void FRUIdentity::flatten(Stream& pel) const
 {
     pel << _type << _size << _flags;