diff --git a/Source/Core/Core/Boot/Boot.cpp b/Source/Core/Core/Boot/Boot.cpp
index 6e0ffebba6..f7dd454484 100644
--- a/Source/Core/Core/Boot/Boot.cpp
+++ b/Source/Core/Core/Boot/Boot.cpp
@@ -267,7 +267,6 @@ bool CBoot::BootUp()
   case SConfig::BOOT_ISO:
   {
     DVDInterface::SetVolumeName(_StartupPara.m_strFilename);
-    DVDInterface::SetDiscInside(DVDInterface::VolumeIsValid());
     if (!DVDInterface::VolumeIsValid())
       return false;
 
@@ -353,8 +352,6 @@ bool CBoot::BootUp()
       BS2Success = EmulatedBS2(dolWii);
     }
 
-    DVDInterface::SetDiscInside(DVDInterface::VolumeIsValid());
-
     if (!BS2Success)
     {
       // Set up MSR and the BAT SPR registers.
@@ -414,8 +411,6 @@ bool CBoot::BootUp()
       DVDInterface::SetVolumeDirectory(_StartupPara.m_strFilename, _StartupPara.bWii);
     }
 
-    DVDInterface::SetDiscInside(DVDInterface::VolumeIsValid());
-
     // Poor man's bootup
     if (_StartupPara.bWii)
     {
@@ -450,13 +445,11 @@ bool CBoot::BootUp()
     else if (!_StartupPara.m_strDefaultISO.empty())
       DVDInterface::SetVolumeName(_StartupPara.m_strDefaultISO);
 
-    DVDInterface::SetDiscInside(DVDInterface::VolumeIsValid());
     break;
 
   // Bootstrap 2 (AKA: Initial Program Loader, "BIOS")
   case SConfig::BOOT_BS2:
   {
-    DVDInterface::SetDiscInside(DVDInterface::VolumeIsValid());
     if (Load_BS2(_StartupPara.m_strBootROM))
     {
       if (LoadMapFromFilename())
diff --git a/Source/Core/Core/HW/DVDInterface.cpp b/Source/Core/Core/HW/DVDInterface.cpp
index bcf3bba2ac..c333627b8a 100644
--- a/Source/Core/Core/HW/DVDInterface.cpp
+++ b/Source/Core/Core/HW/DVDInterface.cpp
@@ -264,7 +264,8 @@ static void EjectDiscCallback(u64 userdata, s64 cyclesLate);
 static void InsertDiscCallback(u64 userdata, s64 cyclesLate);
 static void FinishExecutingCommandCallback(u64 userdata, s64 cycles_late);
 
-void SetLidOpen(bool _bOpen);
+void SetDiscInside(bool disc_inside);
+void SetLidOpen(bool open);
 
 void UpdateInterrupts();
 void GenerateDIInterrupt(DIInterruptType _DVDInterrupt);
@@ -418,6 +419,8 @@ static void DTKStreamingCallback(const std::vector<u8>& audio_data, s64 cycles_l
 
 void Init()
 {
+  _assert_(!VolumeIsValid());
+
   DVDThread::Start();
 
   Reset();
@@ -483,6 +486,7 @@ bool SetVolumeName(const std::string& disc_path)
 {
   DVDThread::WaitUntilIdle();
   s_inserted_volume = DiscIO::CreateVolumeFromFilename(disc_path);
+  SetDiscInside(VolumeIsValid());
   return VolumeIsValid();
 }
 
@@ -492,6 +496,7 @@ bool SetVolumeDirectory(const std::string& full_path, bool is_wii,
   DVDThread::WaitUntilIdle();
   s_inserted_volume =
       DiscIO::CreateVolumeFromDirectory(full_path, is_wii, apploader_path, DOL_path);
+  SetDiscInside(VolumeIsValid());
   return VolumeIsValid();
 }
 
@@ -534,7 +539,6 @@ static void InsertDiscCallback(u64 userdata, s64 cyclesLate)
     SetVolumeName(old_path);
     PanicAlertT("The disc that was about to be inserted couldn't be found.");
   }
-  SetDiscInside(VolumeIsValid());
 
   s_disc_path_to_insert.clear();
 }
diff --git a/Source/Core/Core/HW/DVDInterface.h b/Source/Core/Core/HW/DVDInterface.h
index 410aee8f3e..fb6c97aea5 100644
--- a/Source/Core/Core/HW/DVDInterface.h
+++ b/Source/Core/Core/HW/DVDInterface.h
@@ -108,23 +108,23 @@ void DoState(PointerWrap& p);
 
 void RegisterMMIO(MMIO::Mapping* mmio, u32 base);
 
-// Direct disc access
+// Disc access (don't call GetVolume unless you know that VolumeIsValid() == true)
 const DiscIO::IVolume& GetVolume();
 bool SetVolumeName(const std::string& disc_path);
 bool SetVolumeDirectory(const std::string& disc_path, bool is_wii,
                         const std::string& apploader_path = "", const std::string& DOL_path = "");
 bool VolumeIsValid();
-
-// Disc detection and swapping
-void SetDiscInside(bool _DiscInside);
 bool IsDiscInside();
 void ChangeDiscAsHost(const std::string& new_path);  // Can only be called by the host thread
 void ChangeDiscAsCPU(const std::string& new_path);   // Can only be called by the CPU thread
 
-// DVD Access Functions
+// Direct access to DI for IOS HLE (simpler to implement than how real IOS accesses DI,
+// and lets us skip encrypting/decrypting in some cases)
 bool ChangePartition(u64 offset);
 void ExecuteCommand(u32 command_0, u32 command_1, u32 command_2, u32 output_address,
                     u32 output_length, bool reply_to_ios);
+
+// Used by DVDThread
 void FinishExecutingCommand(ReplyType reply_type, DIInterruptType interrupt_type, s64 cycles_late,
                             const std::vector<u8>& data = std::vector<u8>());