diff --git a/vmm/src/device_manager.rs b/vmm/src/device_manager.rs
index be6f7069c..e6902a4cb 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -2729,6 +2729,11 @@ impl DeviceManager {
             let mut disable_sector0_writes = false;
 
             if disk_cfg.image_type == ImageType::Unknown {
+                warn!(
+                    "DEPRECATION: auto-detection of disk image type is deprecated and will be \
+                    removed in a future release. Please specify image type explicitly."
+                );
+
                 warn!(
                     "No image_type specified - detected as {detected_image_type}. \
                     Configuration updated to persist type across reboots and migrations."