diff --git a/LEGO1/mxdsbuffer.cpp b/LEGO1/mxdsbuffer.cpp
index 4163e39b..2ecefd77 100644
--- a/LEGO1/mxdsbuffer.cpp
+++ b/LEGO1/mxdsbuffer.cpp
@@ -35,3 +35,12 @@ MxResult MxDSBuffer::FUN_100c6780(void* p_buffer, MxU32 p_size)
 	m_mode = 2;
 	return SUCCESS;
 }
+
+// OFFSET: LEGO1 0x100c6f80
+void MxDSBuffer::FUN_100c6f80(MxU32 p_unk)
+{
+	if (p_unk < m_writeOffset)
+	{
+		m_pIntoBuffer2 = p_unk + m_pIntoBuffer;
+	}
+}
diff --git a/LEGO1/mxdsbuffer.h b/LEGO1/mxdsbuffer.h
index e521b47f..1eedc45f 100644
--- a/LEGO1/mxdsbuffer.h
+++ b/LEGO1/mxdsbuffer.h
@@ -19,6 +19,7 @@ class MxDSBuffer : public MxCore {
 	}
 
 	MxResult FUN_100c6780(void* p_buffer, MxU32 p_size);
+	void FUN_100c6f80(MxU32 p_unk);
 
 	inline void* GetBuffer() { return m_pBuffer; }
 	inline MxU32 GetWriteOffset() { return m_writeOffset; }