diff --git a/server/datastore/mysql/hosts.go b/server/datastore/mysql/hosts.go
index df82354692..44f73728a2 100644
--- a/server/datastore/mysql/hosts.go
+++ b/server/datastore/mysql/hosts.go
@@ -2862,14 +2862,14 @@ func (ds *Datastore) ReplaceHostDeviceMapping(ctx context.Context, hid uint, map
 		insPart = ` (?, ?, ?),`
 	)
 
-	// index the mappings by email and source, to quickly check which ones
-	// need to be deleted and inserted
-	toIns := make(map[string]*fleet.HostDeviceMapping)
-	for _, m := range mappings {
-		toIns[m.Email+"\n"+m.Source] = m
-	}
-
 	return ds.withRetryTxx(ctx, func(tx sqlx.ExtContext) error {
+		// index the mappings by email and source, to quickly check which ones
+		// need to be deleted and inserted
+		toIns := make(map[string]*fleet.HostDeviceMapping)
+		for _, m := range mappings {
+			toIns[m.Email+"\n"+m.Source] = m
+		}
+
 		var prevMappings []*fleet.HostDeviceMapping
 		if err := sqlx.SelectContext(ctx, tx, &prevMappings, selStmt, hid); err != nil {
 			return ctxerr.Wrap(ctx, err, "select previous host emails")