diff --git a/Source/Core/Core/HW/DVD/DVDInterface.cpp b/Source/Core/Core/HW/DVD/DVDInterface.cpp
index 9ecb58dc03..ff4d623fa4 100644
--- a/Source/Core/Core/HW/DVD/DVDInterface.cpp
+++ b/Source/Core/Core/HW/DVD/DVDInterface.cpp
@@ -1233,8 +1233,17 @@ void SetHighError(u32 high_error)
 void FinishExecutingCommand(ReplyType reply_type, DIInterruptType interrupt_type, s64 cycles_late,
                             const std::vector<u8>& data)
 {
-  s_DIMAR += s_DILENGTH;
-  s_DILENGTH = 0;
+  // The data parameter contains the requested data iff this was called from DVDThread, and is
+  // empty otherwise. DVDThread is the only source of ReplyType::NoReply and ReplyType::DTK.
+
+  u32 transfer_size = 0;
+  if (reply_type == ReplyType::NoReply)
+    transfer_size = static_cast<u32>(data.size());
+  else if (reply_type == ReplyType::Interrupt || reply_type == ReplyType::IOS)
+    transfer_size = s_DILENGTH;
+
+  s_DIMAR += transfer_size;
+  s_DILENGTH -= transfer_size;
 
   switch (reply_type)
   {