diff --git a/src/emulator/instructions/arithmetic.rs b/src/emulator/instructions/arithmetic.rs
index f376bd2..6a5f77f 100644
--- a/src/emulator/instructions/arithmetic.rs
+++ b/src/emulator/instructions/arithmetic.rs
@@ -57,6 +57,16 @@ bitwise_op!(and, and_reg, &);
 bitwise_op!(or, or_reg, |);
 bitwise_op!(xor, xor_reg, ^);
 
+pub fn cmp_reg(register: Register, state: &mut EmulatorState) {
+    cmp(get_register(register, state), state);
+}
+
+pub fn cmp(byte: u8, state: &mut EmulatorState) {
+    let (result, carry) = state.a.overflowing_sub(byte);
+    state.cc.c = carry;
+    set_cc(state, result);
+}
+
 /// Double precision add - Add B&C, D&E or H&L to H&L
 pub fn dad(register: Register, state: &mut EmulatorState) {
     let num = get_register_pair(register, state);
diff --git a/src/emulator/main.rs b/src/emulator/main.rs
index d41dcc5..5cc4584 100644
--- a/src/emulator/main.rs
+++ b/src/emulator/main.rs
@@ -124,9 +124,11 @@ fn tick(state: &mut EmulatorState) {
         0xa0..=0xa7 => arithmetic::and_reg(register_from_num(instruction & 0xf), state), // ANA
         0xa8..=0xaf => arithmetic::xor_reg(register_from_num(instruction & 0xf), state), // XRA
         0xb0..=0xb7 => arithmetic::or_reg(register_from_num(instruction & 0xf), state),  // ORA
+        0xb8..=0xbf => arithmetic::cmp_reg(register_from_num(instruction & 0xf), state), // CMP
         0xe6 => arithmetic::and(next_byte(), state),                                     // ANI
         0xee => arithmetic::xor(next_byte(), state),                                     // XRI
         0xf6 => arithmetic::or(next_byte(), state),                                      // ORI
+        0xfe => arithmetic::cmp(next_byte(), state),                                     // CPI
 
         _ => not_implemented(state),
     }