diff --git a/vulkan.d b/vulkan.d
index d9eeaa0..4e9d27d 100644
--- a/vulkan.d
+++ b/vulkan.d
@@ -1400,8 +1400,7 @@ Transfer(bool image, T)(Descriptor* desc, T data) if(isArray!(T) || isPointer!(T
   u64 copied = 0;
   while(copied != data.length)
   {
-    data_length    -= copied;
-    u64 copy_length = transfer_length > data_length ? data_length : transfer_length;
+    u64 copy_length = transfer_length > (data_length - copied) ? data_length : transfer_length;
 
     g_vk.transfer_buf.data[0 .. copy_length] = data[copied .. copy_length];