diff --git a/src/Cafe/OS/libs/coreinit/coreinit_Callbacks.cpp b/src/Cafe/OS/libs/coreinit/coreinit_Callbacks.cpp
index 18a36820..403bec61 100644
--- a/src/Cafe/OS/libs/coreinit/coreinit_Callbacks.cpp
+++ b/src/Cafe/OS/libs/coreinit/coreinit_Callbacks.cpp
@@ -1,5 +1,3 @@
-#pragma once
-
 #include "Cafe/OS/libs/coreinit/coreinit_Thread.h"
 #include "util/helpers/fspinlock.h"
 
diff --git a/src/Cafe/OS/libs/coreinit/coreinit_MEM_BlockHeap.cpp b/src/Cafe/OS/libs/coreinit/coreinit_MEM_BlockHeap.cpp
index e4bc6792..33767ddf 100644
--- a/src/Cafe/OS/libs/coreinit/coreinit_MEM_BlockHeap.cpp
+++ b/src/Cafe/OS/libs/coreinit/coreinit_MEM_BlockHeap.cpp
@@ -470,7 +470,7 @@ namespace coreinit
 			// mark current block as free
 			block->isFree = _swapEndianU32(1);
 			// attempt to merge with previous block
-			if (_swapEndianU32(block->previousBlock) != NULL)
+			if (_swapEndianU32(block->previousBlock) != MPTR_NULL)
 			{
 				MPTR previousBlockMPTR = _swapEndianU32(block->previousBlock);
 				MEMBlockHeapTrackDEPR* previousBlock = (MEMBlockHeapTrackDEPR*)memory_getPointerFromVirtualOffset(previousBlockMPTR);
@@ -494,7 +494,7 @@ namespace coreinit
 				}
 			}
 			// attempt to merge with next block
-			if (_swapEndianU32(block->nextBlock) != NULL)
+			if (_swapEndianU32(block->nextBlock) != MPTR_NULL)
 			{
 				MPTR nextBlockMPTR = _swapEndianU32(block->nextBlock);
 				MEMBlockHeapTrackDEPR* nextBlock = (MEMBlockHeapTrackDEPR*)memory_getPointerFromVirtualOffset(nextBlockMPTR);
diff --git a/src/Cafe/OS/libs/coreinit/coreinit_MemoryMapping.cpp b/src/Cafe/OS/libs/coreinit/coreinit_MemoryMapping.cpp
index 26acedce..fe7f4d0b 100644
--- a/src/Cafe/OS/libs/coreinit/coreinit_MemoryMapping.cpp
+++ b/src/Cafe/OS/libs/coreinit/coreinit_MemoryMapping.cpp
@@ -34,7 +34,7 @@ namespace coreinit
 			{
 				debug_printf("coreinitVirtualMemory_alloc(): Unable to allocate memory\n");
 				debugBreakpoint();
-				return NULL;
+				return MPTR_NULL;
 			}
 			// check for overlapping regions
 			OSVirtMemory* virtMemItr = virtualMemoryList;
@@ -66,7 +66,7 @@ namespace coreinit
 				return currentAddress;
 			}
 		}
-		return NULL;
+		return MPTR_NULL;
 	}
 
 	void coreinitExport_OSGetAvailPhysAddrRange(PPCInterpreter_t* hCPU)
diff --git a/src/Cafe/OS/libs/snd_core/ax_ist.cpp b/src/Cafe/OS/libs/snd_core/ax_ist.cpp
index a47b1974..26f975af 100644
--- a/src/Cafe/OS/libs/snd_core/ax_ist.cpp
+++ b/src/Cafe/OS/libs/snd_core/ax_ist.cpp
@@ -99,7 +99,7 @@ namespace snd_core
 		}
 		coreinit::OSInitMutexEx(__AXAppFrameCallbackMutex.GetPtr(), NULL);
 		for (sint32 i = 0; i < AX_DEV_COUNT; i++)
-			__AXDeviceFinalMixCallback[i] = NULL;
+			__AXDeviceFinalMixCallback[i] = MPTR_NULL;
 	}
 
 	sint32 AXRegisterAppFrameCallback(MPTR funcAddr)