diff --git a/src/lib.rs b/src/lib.rs
index 1014f82..c362941 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -182,6 +182,12 @@ pub enum ClockState {
         count: u8,
         addr: u16,
     },
+    Oops {
+        instruction: u8,
+        ops: [u8; 5],
+        count: u8,
+        addr: u16,
+    },
     HoldNmi {
         cycles: u8,
     },
@@ -224,6 +230,17 @@ impl std::fmt::Debug for ClockState {
             ClockState::HoldIrq { cycles } => {
                 f.debug_struct("HoldIrq").field("cycles", cycles).finish()
             }
+            ClockState::Oops {
+                instruction,
+                ops,
+                count,
+                addr,
+            } => f
+                .debug_struct("Oops")
+                .field("instruction", instruction)
+                .field("addr", addr)
+                .field("ops", &&ops[..*count as usize])
+                .finish(),
         }
     }
 }
@@ -232,6 +249,7 @@ enum ExecState {
     Done,
     MoreParams,
     Hold(u8),
+    Oops,
 }
 
 pub enum CPUMMRegisters {
@@ -436,7 +454,14 @@ impl NES {
     }
 
     /// Returns true if more bytes are needed
-    fn exec_instruction(&mut self, ins: u8, mut params: &[u8], held: bool, addr: u16) -> ExecState {
+    fn exec_instruction(
+        &mut self,
+        ins: u8,
+        mut params: &[u8],
+        held: bool,
+        oops: bool,
+        addr: u16,
+    ) -> ExecState {
         macro_rules! inst {
             ($val:expr, $hold:expr, |$($name:pat_param),*| $eval:expr) => {{
                 let hold_time: u8 = ($hold).into();
@@ -588,6 +613,7 @@ impl NES {
                 );
             }),
             0xBD => inst!("LDA abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 self.cpu.a = self.read_abs_x(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -599,6 +625,7 @@ impl NES {
                 );
             }),
             0xB9 => inst!("LDA abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a = self.read_abs_y(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -620,6 +647,7 @@ impl NES {
             0xB1 => inst!("LDA (ind),y", 3, |off| {
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a = self.read(u16::from_le_bytes([low, high]) + self.cpu.y as u16);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -655,6 +683,7 @@ impl NES {
                 );
             }),
             0xBE => inst!("LDX abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.x = self.read_abs_y(low, high);
                 self.cpu.status.set_zero(self.cpu.x == 0);
                 self.cpu.status.set_negative(self.cpu.x & 0x80 == 0x80);
@@ -695,6 +724,7 @@ impl NES {
                 );
             }),
             0xBC => inst!("LDX abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 self.cpu.y = self.read_abs_x(low, high);
                 self.cpu.status.set_zero(self.cpu.y == 0);
                 self.cpu.status.set_negative(self.cpu.y & 0x80 == 0x80);
@@ -956,6 +986,7 @@ impl NES {
                 );
             }),
             0xDD => inst!("CMP abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_x(low, high);
                 let v = self.cpu.a.wrapping_sub(val);
                 self.cpu.status.set_zero(v == 0);
@@ -971,6 +1002,7 @@ impl NES {
                 );
             }),
             0xD9 => inst!("CMP abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_y(low, high);
                 let v = self.cpu.a.wrapping_sub(val);
                 self.cpu.status.set_zero(v == 0);
@@ -1003,9 +1035,9 @@ impl NES {
                 );
             }),
             0xD1 => inst!("CMP (ind),y", 3, |off| {
-                // TODO: iymode
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_y(low, high);
                 let v = self.cpu.a.wrapping_sub(val);
                 self.cpu.status.set_zero(v == 0);
@@ -1163,6 +1195,7 @@ impl NES {
                 );
             }),
             0x7D => inst!("ADC abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_x(low, high);
                 let (a, carry_1) = self.cpu.a.overflowing_add(val);
                 let (a, carry_2) = a.overflowing_add(self.cpu.status.carry().into());
@@ -1181,6 +1214,7 @@ impl NES {
                 );
             }),
             0x79 => inst!("ADC abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_y(low, high);
                 let (a, carry_1) = self.cpu.a.overflowing_add(val);
                 let (a, carry_2) = a.overflowing_add(self.cpu.status.carry().into());
@@ -1221,6 +1255,7 @@ impl NES {
             0x71 => inst!("ADC (ind),y", 3, |off| {
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 let val = self.read(u16::from_le_bytes([low, high]) + self.cpu.y as u16);
                 let (a, carry_1) = self.cpu.a.overflowing_add(val);
                 let (a, carry_2) = a.overflowing_add(self.cpu.status.carry().into());
@@ -1295,6 +1330,7 @@ impl NES {
                 );
             }),
             0xFD => inst!("SBC abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_x(low, high);
                 let (a, carry_1) = self.cpu.a.overflowing_add(!val);
                 let (a, carry_2) = a.overflowing_add(self.cpu.status.carry().into());
@@ -1313,6 +1349,7 @@ impl NES {
                 );
             }),
             0xF9 => inst!("SBC abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 let val = self.read_abs_y(low, high);
                 let (a, carry_1) = self.cpu.a.overflowing_add(!val);
                 let (a, carry_2) = a.overflowing_add(self.cpu.status.carry().into());
@@ -1353,6 +1390,7 @@ impl NES {
             0xF1 => inst!("SBC (ind),y", 3, |off| {
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 let val = self.read(u16::from_le_bytes([low, high]) + self.cpu.y as u16);
                 let (a, carry_1) = self.cpu.a.overflowing_add(!val);
                 let (a, carry_2) = a.overflowing_add(self.cpu.status.carry().into());
@@ -1502,7 +1540,7 @@ impl NES {
                 );
             }),
             0x1D => inst!("ORA abs,x", 1, |low, high| {
-                // TODO: page crossing
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 self.cpu.a |= self.read_abs_x(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1514,6 +1552,7 @@ impl NES {
                 );
             }),
             0x19 => inst!("ORA abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a |= self.read_abs_y(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1540,6 +1579,10 @@ impl NES {
             0x11 => inst!("ORA (ind),y", 3, |off| {
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
+                if !oops && low.checked_add(self.cpu.y).is_none() {
+                    return ExecState::Oops;
+                }
                 self.cpu.a |= self.read(u16::from_le_bytes([low, high]) + self.cpu.y as u16);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1580,6 +1623,7 @@ impl NES {
                 );
             }),
             0x3D => inst!("AND abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 self.cpu.a &= self.read_abs_x(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1591,6 +1635,7 @@ impl NES {
                 );
             }),
             0x39 => inst!("AND abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a &= self.read_abs_y(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1617,6 +1662,7 @@ impl NES {
             0x31 => inst!("AND (ind),y", 3, |off| {
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a &= self.read(u16::from_le_bytes([low, high]) + self.cpu.y as u16);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1657,6 +1703,7 @@ impl NES {
                 );
             }),
             0x5D => inst!("EOR abs,x", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.x).is_none() { return ExecState::Oops; }
                 self.cpu.a ^= self.read_abs_x(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1668,6 +1715,7 @@ impl NES {
                 );
             }),
             0x59 => inst!("EOR abs,y", 1, |low, high| {
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a ^= self.read_abs_y(low, high);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1694,6 +1742,7 @@ impl NES {
             0x51 => inst!("EOR (ind),y", 3, |off| {
                 let low = self.read_abs(off, 0);
                 let high = self.read_abs(off.wrapping_add(1), 0);
+                if !oops && low.checked_add(self.cpu.y).is_none() { return ExecState::Oops; }
                 self.cpu.a ^= self.read(u16::from_le_bytes([low, high]) + self.cpu.y as u16);
                 self.cpu.status.set_zero(self.cpu.a == 0);
                 self.cpu.status.set_negative(self.cpu.a & 0x80 == 0x80);
@@ -1973,39 +2022,32 @@ impl NES {
                 }
             }
             ClockState::ReadInstruction => {
-                // if self.cpu.nmi_pending {
-                //     self.cpu.nmi_pending = false;
-                //     writeln!(self.debug_log, "NMI detected").unwrap();
-                //     ClockState::HoldNmi { cycles: 5 }
-                // } else if !self.cpu.status.interrupt_disable()
-                //     && (self.ppu.irq_waiting() || self.apu.irq_waiting())
-                // {
-                //     // TODO: handle proper irq detection
-                //     writeln!(self.debug_log, "IRQ detected").unwrap();
-                //     ClockState::HoldIrq { cycles: 6 }
-                // } else
-                {
-                    let addr = self.cpu.pc;
-                    let instruction = self.read(self.cpu.pc);
-                    if instruction != 0x02 {
-                        self.cpu.pc = self.cpu.pc.wrapping_add(1);
-                    }
-                    match self.exec_instruction(instruction, &[], false, addr) {
-                        ExecState::Done => ClockState::ReadInstruction,
-                        ExecState::MoreParams => ClockState::ReadOperands {
-                            instruction,
-                            ops: [0u8; 5],
-                            count: 0,
-                            addr,
-                        },
-                        ExecState::Hold(cycles) => ClockState::Hold {
-                            cycles,
-                            instruction,
-                            ops: [0u8; 5],
-                            count: 0,
-                            addr,
-                        },
-                    }
+                let addr = self.cpu.pc;
+                let instruction = self.read(self.cpu.pc);
+                if instruction != 0x02 {
+                    self.cpu.pc = self.cpu.pc.wrapping_add(1);
+                }
+                match self.exec_instruction(instruction, &[], false, false, addr) {
+                    ExecState::Done => ClockState::ReadInstruction,
+                    ExecState::MoreParams => ClockState::ReadOperands {
+                        instruction,
+                        ops: [0u8; 5],
+                        count: 0,
+                        addr,
+                    },
+                    ExecState::Hold(cycles) => ClockState::Hold {
+                        cycles,
+                        instruction,
+                        ops: [0u8; 5],
+                        count: 0,
+                        addr,
+                    },
+                    ExecState::Oops => ClockState::Oops {
+                        instruction,
+                        ops: [0u8; 5],
+                        count: 0,
+                        addr,
+                    },
                 }
             }
             ClockState::ReadOperands {
@@ -2019,7 +2061,13 @@ impl NES {
                 }
                 ops[count as usize] = self.read(self.cpu.pc);
                 self.cpu.pc = self.cpu.pc.wrapping_add(1);
-                match self.exec_instruction(instruction, &ops[..count as usize + 1], false, addr) {
+                match self.exec_instruction(
+                    instruction,
+                    &ops[..count as usize + 1],
+                    false,
+                    false,
+                    addr,
+                ) {
                     ExecState::Done => ClockState::ReadInstruction,
                     ExecState::MoreParams => ClockState::ReadOperands {
                         instruction,
@@ -2034,6 +2082,12 @@ impl NES {
                         count: count + 1,
                         addr,
                     },
+                    ExecState::Oops => ClockState::Oops {
+                        instruction,
+                        ops,
+                        count: count + 1,
+                        addr,
+                    },
                 }
             }
             ClockState::Hold {
@@ -2044,15 +2098,24 @@ impl NES {
                 addr,
             } => {
                 if cycles == 0 {
-                    match self.exec_instruction(instruction, &ops[..count as usize], true, addr) {
+                    match self.exec_instruction(
+                        instruction,
+                        &ops[..count as usize],
+                        true,
+                        false,
+                        addr,
+                    ) {
                         ExecState::Done => ClockState::ReadInstruction,
-                        ExecState::MoreParams => ClockState::ReadOperands {
+                        ExecState::MoreParams => {
+                            panic!("Should never return MoreParams after holding")
+                        }
+                        ExecState::Hold(_) => panic!("Should never return Hold after holding"),
+                        ExecState::Oops => ClockState::Oops {
                             instruction,
                             ops,
-                            count: count + 1,
+                            count,
                             addr,
                         },
-                        ExecState::Hold(_) => panic!("Should never return Hold after holding"),
                     }
                 } else {
                     ClockState::Hold {
@@ -2064,6 +2127,17 @@ impl NES {
                     }
                 }
             }
+            ClockState::Oops {
+                instruction,
+                ops,
+                count,
+                addr,
+            } => {
+                match self.exec_instruction(instruction, &ops[..count as usize], true, true, addr) {
+                    ExecState::Done => ClockState::ReadInstruction,
+                    _ => panic!("Must execute after oops"),
+                }
+            }
         };
         if self.cpu.clock_state == ClockState::ReadInstruction {
             if self.cpu.nmi_pending {
diff --git a/src/main.rs b/src/main.rs
index 66ce7f0..b3d80cf 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -26,8 +26,8 @@ use tracing_subscriber::EnvFilter;
 // const ROM_FILE: &str = concat!(env!("ROM_DIR"), "/", "ppu_fill_red.nes");
 // const ROM_FILE: &str = concat!(env!("ROM_DIR"), "/", "ppu_fill_name_table.nes");
 // const ROM_FILE: &str = concat!(env!("ROM_DIR"), "/", "int_nmi_exit_timing.nes");
-const ROM_FILE: &str = "./Super Mario Bros. (World).nes";
-// const ROM_FILE: &str = "./cpu_timing_test.nes";
+// const ROM_FILE: &str = "./Super Mario Bros. (World).nes";
+const ROM_FILE: &str = "./cpu_timing_test.nes";
 
 extern crate nes_emu;