diff --git a/internal/bucket/object/lock/lock.go b/internal/bucket/object/lock/lock.go
index 6ba9857a2..572e9db66 100644
--- a/internal/bucket/object/lock/lock.go
+++ b/internal/bucket/object/lock/lock.go
@@ -572,6 +572,7 @@ func FilterObjectLockMetadata(metadata map[string]string, filterRetention, filte
 	dst := metadata
 	var copied bool
 	delKey := func(key string) {
+		key = strings.ToLower(key)
 		if _, ok := metadata[key]; !ok {
 			return
 		}
diff --git a/internal/bucket/object/lock/lock_test.go b/internal/bucket/object/lock/lock_test.go
index d800a5332..91313482d 100644
--- a/internal/bucket/object/lock/lock_test.go
+++ b/internal/bucket/object/lock/lock_test.go
@@ -606,7 +606,7 @@ func TestFilterObjectLockMetadata(t *testing.T) {
 
 	for i, tt := range tests {
 		o := FilterObjectLockMetadata(tt.metadata, tt.filterRetention, tt.filterLegalHold)
-		if !reflect.DeepEqual(o, tt.metadata) {
+		if !reflect.DeepEqual(o, tt.expected) {
 			t.Fatalf("Case %d expected %v, got %v", i, tt.metadata, o)
 		}
 	}