diff --git a/Database/AthenaPOOL/RootFileTools/src/merge.cxx b/Database/AthenaPOOL/RootFileTools/src/merge.cxx
index cfcd11cddb02bac7e872aac1410e1aa82fb8c412..2fbfbe428e2571fd2a3a21ba2c11118c0583f105 100644
--- a/Database/AthenaPOOL/RootFileTools/src/merge.cxx
+++ b/Database/AthenaPOOL/RootFileTools/src/merge.cxx
@@ -272,7 +272,7 @@ bool DbDatabaseMerger::empty(const std::string& fid, const std::set<std::string>
 }
 
 /// Check if a database exists
-bool DbDatabaseMerger::exists(const std::string& fid, bool dbg) const {
+bool DbDatabaseMerger::exists(const std::string& fid, bool /*dbg*/) const {
   Bool_t result = gSystem->AccessPathName(fid.c_str(), kFileExists);
   return result == kFALSE;
 }