diff --git a/unittest/formats/test_file_operations.cpp b/unittest/formats/test_file_operations.cpp
index 06b29d0189..08f2b05937 100644
--- a/unittest/formats/test_file_operations.cpp
+++ b/unittest/formats/test_file_operations.cpp
@@ -612,6 +612,10 @@ TEST_F(FileOperationsTest, read_data_fix)
     EXPECT_EQ(lmp->atom->tag[GETIDX(8)], 8);
     EXPECT_EQ(lmp->atom->tag[GETIDX(9)], 9);
     EXPECT_EQ(lmp->atom->tag[GETIDX(10)], 10);
+
+    // clean up
+    delete_file("test_mol_id_merge.data");
+    delete_file("test_mol_id.data");
 }
 
 int main(int argc, char **argv)