diff --git a/performance-metrics/src/performance_tests.rs b/performance-metrics/src/performance_tests.rs
index 7eb07f368..c3787f4da 100644
--- a/performance-metrics/src/performance_tests.rs
+++ b/performance-metrics/src/performance_tests.rs
@@ -442,6 +442,8 @@ pub fn performance_block_io(control: &PerformanceTestControl) -> f64 {
         format!("path={test_file},queue_size={queue_size},num_queues={num_queues}");
     if test_file == OVERLAY_WITH_QCOW2_BACKING || test_file == OVERLAY_WITH_RAW_BACKING {
         test_disk_arg.push_str(",image_type=qcow2,backing_files=on");
+    } else if test_file == BLK_IO_TEST_IMG {
+        test_disk_arg.push_str(",image_type=raw");
     }
 
     let mut child = GuestCommand::new(&guest)