diff --git a/LEGO1/mxdiskstreamprovider.cpp b/LEGO1/mxdiskstreamprovider.cpp
index 2aa25e02..624b3cfc 100644
--- a/LEGO1/mxdiskstreamprovider.cpp
+++ b/LEGO1/mxdiskstreamprovider.cpp
@@ -130,55 +130,63 @@ MxResult MxDiskStreamProvider::FUN_100d1780(MxDSStreamingAction* p_action)
 // FUNCTION: LEGO1 0x100d18f0
 void MxDiskStreamProvider::PerformWork()
 {
-	MxDSStreamingAction* action;
+	MxDiskStreamController* controller = (MxDiskStreamController*) m_pLookup;
+	MxDSStreamingAction* streamingAction = NULL;
+
 	{
 		MxAutoLocker lock(&m_criticalSection);
-		if (m_list.size() != 0 && !FUN_100d1af0((MxDSStreamingAction*) m_list.front())) {
-			MxThread::Sleep(500);
-			m_busySemaphore.Release(1);
-			return;
+		if (!m_list.empty()) {
+			streamingAction = (MxDSStreamingAction*) m_list.front();
+
+			if (streamingAction && !FUN_100d1af0(streamingAction)) {
+				m_thread.Sleep(500);
+				m_busySemaphore.Release(1);
+				return;
+			}
 		}
 	}
 
 	{
 		MxAutoLocker lock(&m_criticalSection);
-		if (m_list.size() != 0) {
-			action = (MxDSStreamingAction*) m_list.front();
-			m_list.pop_front();
 
-			// TODO delete lock here (could be an inline function for locking & popping list)
-			if (action->GetUnknowna0()->GetWriteOffset() < 0x20000) {
-				g_unk0x10102878--;
+		if (!m_list.PopFrontStreamingAction(streamingAction))
+			return;
+	}
+
+	if (streamingAction->GetUnknowna0()->GetWriteOffset() < 0x20000) {
+		g_unk0x10102878--;
+	}
+
+	MxDSBuffer* buffer = streamingAction->GetUnknowna0();
+
+	if (m_pFile->GetPosition() == streamingAction->GetBufferOffset() ||
+		m_pFile->Seek(streamingAction->GetBufferOffset(), 0) == 0) {
+		buffer->SetUnknown14(m_pFile->GetPosition());
+
+		if (m_pFile->ReadToBuffer(buffer) == SUCCESS) {
+			buffer->SetUnknown1c(m_pFile->GetPosition());
+
+			if (streamingAction->GetUnknown9c() > 0) {
+				FUN_100d1b20(streamingAction);
 			}
-
-			MxDSBuffer* buffer = action->GetUnknowna0();
-			if (m_pFile->GetPosition() == action->GetUnknowna0()->GetWriteOffset() ||
-				m_pFile->Seek(action->GetBufferOffset(), 0) == 0) {
-				buffer->SetUnknown14(m_pFile->GetPosition());
-				if (m_pFile->ReadToBuffer(buffer) == SUCCESS) {
-					buffer->SetUnknown1c(m_pFile->GetPosition());
-					if (action->GetUnknown9c() < 1) {
-						if (m_pLookup == NULL || !((MxDiskStreamController*) m_pLookup)->GetUnk0xc4()) {
-							((MxDiskStreamController*) m_pLookup)->FUN_100c8670(action);
-						}
-						else {
-							((MxDiskStreamController*) m_pLookup)->FUN_100c7f40(action);
-						}
-					}
-					else {
-						FUN_100d1b20(action);
-					}
-
-					action = NULL;
+			else {
+				if (m_pLookup == NULL || !((MxDiskStreamController*) m_pLookup)->GetUnk0xc4()) {
+					controller->FUN_100c8670(streamingAction);
+				}
+				else {
+					controller->FUN_100c7f40(streamingAction);
 				}
 			}
+
+			streamingAction = NULL;
 		}
 	}
 
-	if (action) {
-		((MxDiskStreamController*) m_pLookup)->FUN_100c8670(action);
+	if (streamingAction) {
+		controller->FUN_100c8670(streamingAction);
 	}
-	MxThread::Sleep(0);
+
+	m_thread.Sleep(0);
 }
 
 // FUNCTION: LEGO1 0x100d1af0
diff --git a/LEGO1/mxdssource.cpp b/LEGO1/mxdssource.cpp
index 4e4cf65d..c2d86abb 100644
--- a/LEGO1/mxdssource.cpp
+++ b/LEGO1/mxdssource.cpp
@@ -2,6 +2,8 @@
 
 #include "mxdsbuffer.h"
 
+DECOMP_SIZE_ASSERT(MxDSSource, 0x14)
+
 // FUNCTION: LEGO1 0x100bffd0
 MxResult MxDSSource::ReadToBuffer(MxDSBuffer* p_buffer)
 {
diff --git a/LEGO1/mxdssource.h b/LEGO1/mxdssource.h
index c8279446..711ba110 100644
--- a/LEGO1/mxdssource.h
+++ b/LEGO1/mxdssource.h
@@ -6,6 +6,7 @@
 class MxDSBuffer;
 
 // VTABLE: LEGO1 0x100dc8c8
+// SIZE 0x14
 class MxDSSource : public MxCore {
 public:
 	MxDSSource() : m_lengthInDWords(0), m_pBuffer(NULL), m_position(-1) {}
@@ -35,9 +36,9 @@ class MxDSSource : public MxCore {
 	inline MxLong GetPosition() const { return m_position; }
 
 protected:
-	MxULong m_lengthInDWords;
-	MxU32* m_pBuffer;
-	MxLong m_position;
+	MxULong m_lengthInDWords; // 0x08
+	MxU32* m_pBuffer;         // 0x0c
+	MxLong m_position;        // 0x10
 };
 
 #endif // MXDSSOURCE_H
diff --git a/LEGO1/mxstreamlist.h b/LEGO1/mxstreamlist.h
index 9b65c53d..6aa63de0 100644
--- a/LEGO1/mxstreamlist.h
+++ b/LEGO1/mxstreamlist.h
@@ -1,7 +1,7 @@
 #ifndef MXSTREAMLIST_H
 #define MXSTREAMLIST_H
 
-#include "mxdsaction.h"
+#include "mxdsstreamingaction.h"
 #include "mxdssubscriber.h"
 #include "mxnextactiondatastart.h"
 #include "mxstl/stlcompat.h"
@@ -24,6 +24,18 @@ class MxStreamList : public list<T> {
 class MxStreamListMxDSAction : public MxStreamList<MxDSAction*> {
 public:
 	MxDSAction* Find(MxDSAction* p_action, MxBool p_delete);
+
+	// There chance this list actually holds MxDSStreamingListAction
+	// instead of MxDSAction. Until then, we use this helper.
+	MxBool PopFrontStreamingAction(MxDSStreamingAction*& p_obj)
+	{
+		if (empty())
+			return FALSE;
+
+		p_obj = (MxDSStreamingAction*) front();
+		pop_front();
+		return TRUE;
+	}
 };
 
 // SIZE 0xc
diff --git a/LEGO1/mxstreamprovider.h b/LEGO1/mxstreamprovider.h
index ecbe9ab4..73804684 100644
--- a/LEGO1/mxstreamprovider.h
+++ b/LEGO1/mxstreamprovider.h
@@ -34,8 +34,8 @@ class MxStreamProvider : public MxCore {
 	virtual MxU32* GetBufferForDWords() = 0;                           // vtable+0x28
 
 protected:
-	MxStreamController* m_pLookup;
-	MxDSFile* m_pFile;
+	MxStreamController* m_pLookup; // 0x08
+	MxDSFile* m_pFile;             // 0x0c
 };
 
 #endif // MXSTREAMPROVIDER_H
diff --git a/LEGO1/mxthread.h b/LEGO1/mxthread.h
index 3695b29f..fa85b83d 100644
--- a/LEGO1/mxthread.h
+++ b/LEGO1/mxthread.h
@@ -16,8 +16,7 @@ class MxThread {
 	MxResult Start(MxS32 p_stack, MxS32 p_flag);
 
 	void Terminate();
-
-	static void Sleep(MxS32 p_milliseconds);
+	void Sleep(MxS32 p_milliseconds);
 
 	// Inferred, not in DLL
 	inline MxBool IsRunning() { return m_running; }