diff --git a/app/src/main/java/eu/depau/ddroid/services/UsbAPIWriteService.kt b/app/src/main/java/eu/depau/ddroid/services/UsbAPIWriteService.kt
index 2d5df85..5d4c596 100644
--- a/app/src/main/java/eu/depau/ddroid/services/UsbAPIWriteService.kt
+++ b/app/src/main/java/eu/depau/ddroid/services/UsbAPIWriteService.kt
@@ -12,7 +12,8 @@ import eu.depau.ddroid.utils.name
 import java.nio.ByteBuffer
 
 class UsbAPIWriteService : UsbWriteService("UsbAPIWriteService") {
-    val DD_BLOCKSIZE = 4096
+    // 512 * 32 bytes = USB max transfer size
+    val DD_BLOCKSIZE = 512 * 32 * 64  // 1 MB
 
     class Action {
         val WRITE_IMAGE = "eu.depau.ddroid.action.API_WRITE_IMAGE"