diff --git a/Makefile.arm9 b/Makefile.arm9
index 899eee9..cdcf5b5 100644
--- a/Makefile.arm9
+++ b/Makefile.arm9
@@ -35,7 +35,7 @@
 			-Wformat=2 -Wlogical-op -Wmissing-include-dirs -Wredundant-decls \
 			-Wshadow -Wsign-conversion -fstrict-overflow -Wstrict-overflow=5 \
 			-Wswitch-default -Wundef -fstrict-aliasing -Wstrict-aliasing \
-			-std=c11 -O2 -flto -mword-relocations -fomit-frame-pointer \
+			-std=c11 -Og -mword-relocations -fomit-frame-pointer \
 			-ffast-math -ffunction-sections $(ARCH)
 
 CFLAGS	+=	$(INCLUDE) -DARM9 $(DEFINES)
diff --git a/source/arm9/debug.c b/source/arm9/debug.c
new file mode 100644
index 0000000..e50d211
--- /dev/null
+++ b/source/arm9/debug.c
@@ -0,0 +1,64 @@
+#include <stdio.h>
+#include <string.h>
+#include "types.h"
+#include "mem_map.h"
+#include "console.h"
+
+void NORETURN guruMeditation(u8 type, u32 *excStack, u32 *stackPointer)
+{
+	const char *typeStr[3] = {"Undefined instruction", "Prefetch abort", "Data abort"};
+	u32 realPc, instSize = 4;
+
+
+	consoleInit(0, NULL);
+
+	if(excStack[1] & 0x20) instSize = 2; // Processor was in Thumb mode?
+	if(type == 2) realPc = excStack[15] - (instSize * 2); // Data abort
+	else realPc = excStack[15] - instSize; // Other
+
+	printf("\x1b[41m\x1b[0J\x1b[9CGuru Meditation Error!\n\n%s:\nCPSR: 0x%X\n", typeStr[type], excStack[1]);
+	printf("r0 = 0x%08X r8  = 0x%08X\n"
+			"r1 = 0x%08X r9  = 0x%08X\n"
+			"r2 = 0x%08X r10 = 0x%08X\n"
+			"r3 = 0x%08X r11 = 0x%08X\n"
+			"r4 = 0x%08X r12 = 0x%08X\n"
+			"r5 = 0x%08X sp  = 0x%08X\n"
+			"r6 = 0x%08X lr  = 0x%08X\n"
+			"r7 = 0x%08X pc  = 0x%08X\n\n",
+			excStack[2], excStack[10],
+			excStack[3], excStack[11],
+			excStack[4], excStack[12],
+			excStack[5], excStack[13],
+			excStack[6], excStack[14],
+			excStack[7], (u32)stackPointer,
+			excStack[8], excStack[0],
+			excStack[9], realPc);
+
+	// make sure we can actually dump the stack without triggering another fault.
+	if((stackPointer >= A9_RAM_BASE) && (stackPointer < A9_RAM_BASE + A9_RAM_SIZE))
+	{
+		puts("Stack dump:");
+		for(u32 i = 0; i < 15; i++)
+		{
+			printf("0x%08X: %08X %08X\n", (u32)stackPointer, stackPointer[0], stackPointer[1]);
+			stackPointer += 2;
+		}
+	}
+
+	// avoid fs corruptions
+	unmount_fs();
+	devs_close();
+
+	while(1);
+}
+
+void NORETURN panic()
+{
+	printf("\x1b[41m\x1b[0J\x1b[9CGPANIC!!!\n");
+	
+	unmount_fs();
+	devs_close();
+	
+	while(1);
+}
+
diff --git a/source/arm9/dev.c b/source/arm9/dev.c
index 6dcfd46..b4ded9b 100644
--- a/source/arm9/dev.c
+++ b/source/arm9/dev.c
@@ -126,6 +126,11 @@
 {
 	if(!dev_sd.initialized)
 		return false;
+		
+	if((u32)buf & 3) panic();
+		
+	if(size < 0x200)
+		panic();
 	
 	return !sdmmc_sdcard_readsectors(offset >> 9, size >> 9, buf);
 }
@@ -134,6 +139,11 @@
 {
 	if(!dev_sd.initialized)
 		return false;
+		
+	if((u32)buf & 3) panic();
+		
+	if(size < 0x200)
+		panic();
 	
 	return !sdmmc_sdcard_writesectors(offset >> 9, size >> 9, buf);
 }
@@ -170,6 +180,11 @@
 {
 	if(!dev_rnand.initialized)
 		return false;
+		
+	if((u32)buf & 3) panic();
+		
+	if(size < 0x200)
+		panic();
 	
 	return !sdmmc_nand_readsectors(offset >> 9, size >> 9, buf);
 }
@@ -178,6 +193,11 @@
 {
 	if(!dev_rnand.initialized)
 		return false;
+		
+	if((u32)buf & 3) panic();
+		
+	if(size < 0x200)
+		panic();
 	
 	return !sdmmc_nand_writesectors(offset >> 9, size >> 9, buf);
 }
@@ -300,6 +320,11 @@
 {
 	//printf("Decnand read: offset: 0x%X, size: 0x%X\n", (unsigned int)offset, (unsigned int)size);
 	if(!dev_dnand.dev.initialized) return false;
+	
+	if((u32)buf & 3) panic();
+		
+	if(size < 0x200)
+		panic();
 
 	AES_ctx *ctx;
 	nand_partition_struct *partition = find_partition(offset, size);
@@ -330,6 +355,11 @@
 {
 	if(!dev_dnand.dev.initialized)
 		return false;
+		
+	if((u32)buf & 3) panic();
+		
+	if(size < 0x200)
+		panic();
 	
 	//return !sdmmc_nand_writesectors(offset >> 9, size >> 9, buf);
 	printf("Decnand write not implemented!\n");
diff --git a/source/arm9/gurumeditation.c b/source/arm9/gurumeditation.c
deleted file mode 100644
index 264839c..0000000
--- a/source/arm9/gurumeditation.c
+++ /dev/null
@@ -1,49 +0,0 @@
-#include <stdio.h>
-#include <string.h>
-#include "types.h"
-#include "mem_map.h"
-#include "console.h"
-
-void NORETURN guruMeditation(u8 type, u32 *excStack, u32 *stackPointer)
-{
-	const char *typeStr[3] = {"Undefined instruction", "Prefetch abort", "Data abort"};
-	u32 realPc, instSize = 4;
-
-
-	consoleInit(0, NULL);
-
-	if(excStack[1] & 0x20) instSize = 2; // Processor was in Thumb mode?
-	if(type == 2) realPc = excStack[15] - (instSize * 2); // Data abort
-	else realPc = excStack[15] - instSize; // Other
-
-	printf("\x1b[41m\x1b[0J\x1b[9CGuru Meditation Error!\n\n%s:\nCPSR: 0x%X\n", typeStr[type], excStack[1]);
-	printf("r0 = 0x%08X r8  = 0x%08X\n"
-			"r1 = 0x%08X r9  = 0x%08X\n"
-			"r2 = 0x%08X r10 = 0x%08X\n"
-			"r3 = 0x%08X r11 = 0x%08X\n"
-			"r4 = 0x%08X r12 = 0x%08X\n"
-			"r5 = 0x%08X sp  = 0x%08X\n"
-			"r6 = 0x%08X lr  = 0x%08X\n"
-			"r7 = 0x%08X pc  = 0x%08X\n\n",
-			excStack[2], excStack[10],
-			excStack[3], excStack[11],
-			excStack[4], excStack[12],
-			excStack[5], excStack[13],
-			excStack[6], excStack[14],
-			excStack[7], (u32)stackPointer,
-			excStack[8], excStack[0],
-			excStack[9], realPc);
-
-	// make sure we can actually dump the stack without triggering another fault.
-	if((stackPointer >= A9_RAM_BASE) && (stackPointer < A9_RAM_BASE + A9_RAM_SIZE))
-	{
-		puts("Stack dump:");
-		for(u32 i = 0; i < 15; i++)
-		{
-			printf("0x%08X: %08X %08X\n", (u32)stackPointer, stackPointer[0], stackPointer[1]);
-			stackPointer += 2;
-		}
-	}
-
-	while(1);
-}