diff --git a/desmume/src/GPU.cpp b/desmume/src/GPU.cpp
index 47b5dcbc6..95f9bed71 100644
--- a/desmume/src/GPU.cpp
+++ b/desmume/src/GPU.cpp
@@ -51,6 +51,7 @@
 #include "render3D.h"
 #include "GPU_osd.h"
 #include "debug.h"
+#include "NDSSystem.h"
 
 //#define CHECKSPRITES
 
@@ -430,7 +431,8 @@ u16 GPU::blend(u16 colA, u16 colB)
 
 void GPU_setMasterBrightness (GPU *gpu, u16 val)
 {
-	gpu->MasterBrightFactor = (val & 0x1F);
+	if(!nds.isInVblank()) PROGINFO("Changing master brightness outside of vblank\n");
+ 	gpu->MasterBrightFactor = (val & 0x1F);
 	gpu->MasterBrightMode	= (val>>14);
 }
 
diff --git a/desmume/src/MMU.cpp b/desmume/src/MMU.cpp
index 5562e37b9..3f21c915e 100644
--- a/desmume/src/MMU.cpp
+++ b/desmume/src/MMU.cpp
@@ -597,6 +597,8 @@ static inline void MMU_VRAMmapControl(u8 block, u8 VRAMBankCnt)
 	
 	u32	vram_map_addr = 0xFFFFFFFF;
 	u8	*LCD_addr = LCDdst[block];
+
+	bool changingTexOrTexPalette = false;
 	
 	switch (VRAMBankCnt & 0x07)
 	{
@@ -674,6 +676,7 @@ static inline void MMU_VRAMmapControl(u8 block, u8 VRAMBankCnt)
 				case 3:		// D
 					// Textures
 					{
+						changingTexOrTexPalette = true;
 						int slot_index = (VRAMBankCnt >> 3) & 0x3;
 						ARM9Mem.textureSlotAddr[slot_index] = LCD_addr;
 						gpu3D->NDS_3D_VramReconfigureSignal();
@@ -682,6 +685,7 @@ static inline void MMU_VRAMmapControl(u8 block, u8 VRAMBankCnt)
 					}
 				break;
 				case 4:		// E
+					changingTexOrTexPalette = true;
 					ARM9Mem.texPalSlot[0] = LCD_addr;
 					ARM9Mem.texPalSlot[1] = LCD_addr+0x4000;
 					ARM9Mem.texPalSlot[2] = LCD_addr+0x8000;
@@ -691,6 +695,7 @@ static inline void MMU_VRAMmapControl(u8 block, u8 VRAMBankCnt)
 				case 5:		// F
 				case 6:		// G
 				{
+					changingTexOrTexPalette = true;
 					u8 tmp_slot = ((VRAMBankCnt >> 3) & 0x01) + (((VRAMBankCnt >> 4) & 0x01)*4);
 					ARM9Mem.texPalSlot[tmp_slot] = LCD_addr;
 					gpu3D->NDS_3D_VramReconfigureSignal();
@@ -746,6 +751,11 @@ static inline void MMU_VRAMmapControl(u8 block, u8 VRAMBankCnt)
 		break;
 	}
 
+	if(changingTexOrTexPalette && !nds.isIn3dVblank())
+	{
+		PROGINFO("Changing texture or texture palette mappings outside of 3d vblank\n");
+	}
+
 	if (vram_map_addr != 0xFFFFFFFF)
 	{
 		u8	engine = (vram_map_addr >> 21);
diff --git a/desmume/src/NDSSystem.h b/desmume/src/NDSSystem.h
index 70654f2b7..07dfeefec 100644
--- a/desmume/src/NDSSystem.h
+++ b/desmume/src/NDSSystem.h
@@ -131,6 +131,9 @@ typedef struct
 	s32 idleCycles;
 	s32 runCycleCollector[16];
 	s32 idleFrameCounter;
+
+	bool isInVblank() const { return VCount >= 192; } 
+	bool isIn3dVblank() const { return VCount >= 192 && VCount<215; } 
 } NDSSystem;
 
 /** /brief A touchscreen calibration point.