diff --git a/cpu.c b/cpu.c
index 968fcd8..594c462 100644
--- a/cpu.c
+++ b/cpu.c
@@ -81,10 +81,8 @@ peek(uint16_t addr)
 static uint16_t
 peek16(uint16_t addr)
 {
-	MEMORY_MIRROR(addr);
-
 	/* bytes are stored in little-endian (low then high) */
-	return (uint16_t)memory[addr] | ((uint16_t)memory[addr + 1] << 8);
+	return peek(addr) | (peek(addr + 1) << 8);
 }
 
 static void
@@ -108,7 +106,7 @@ memwrite16(uint16_t addr, uint16_t word)
 static uint8_t
 opcode_arg(enum addressing_mode mode)
 {
-	uint8_t arg, val;
+	uint16_t arg, val;
 
 	if (mode != AM_ABS && mode != AM_ABS_X && mode != AM_ABS_Y)
 		arg = peek(regs.pc++);
@@ -149,14 +147,15 @@ opcode_arg(enum addressing_mode mode)
 		abort();
 	}
 
+	printf("arg: $%04X $%04X\n", arg, val);
+
 	return val;
 }
 
 static uint16_t
 opcode_mem(enum addressing_mode mode)
 {
-	uint8_t arg;
-	uint16_t val;
+	uint16_t arg, val;
 
 	if (mode != AM_ABS && mode != AM_ABS_X && mode != AM_ABS_Y)
 		arg = peek(regs.pc++);
@@ -173,6 +172,7 @@ opcode_mem(enum addressing_mode mode)
 	case AM_ZP_Y:
 		val = (arg + regs.y) % 256;
 		break;
+	case AM_IMM:
 	case AM_ABS:
 		val = arg;
 		break;
@@ -1059,7 +1059,7 @@ interpret(void)
 			cycles += 2;
 			break;
 		case 0x4c:
-			jmp(opcode_arg(AM_ABS));
+			jmp(opcode_mem(AM_ABS));
 			cycles += 3;
 			break;
 		case 0x6c:
@@ -1111,7 +1111,7 @@ interpret(void)
 			cycles += 5;
 			break;
 		case 0xa2:
-			ldx(opcode_arg(AM_IMM));
+			ldx(opcode_mem(AM_IMM));
 			cycles += 2;
 			break;
 		case 0xa6:
@@ -1467,8 +1467,8 @@ main(int argc, char *argv[])
 		return 1;
 	}
 
-	memwrite16(0xFFFC, 0x8000);
-	regs.pc = 0x8000;
+	memwrite16(0xFFFC, 0xC000);
+	regs.pc = 0xC000;
 
 	printf("status: %i%i%i%i%i%i%i%i\n", regs.status.carry,
 	    regs.status.zero, regs.status.interrupt_disable,