diff --git a/src/cpu/instructions.rs b/src/cpu/instructions.rs
index 7a4f356..07982b2 100644
--- a/src/cpu/instructions.rs
+++ b/src/cpu/instructions.rs
@@ -25,6 +25,9 @@ pub struct RunnableInstruction {
 impl RunnableInstruction {
     /// `from_data` will produce an instruction from the given data and return the data after
     /// processing that operation.
+    ///
+    /// # Errors
+    /// Returns an error if the instruction couldn't be parsed.
     pub fn from_data(data: &[u8]) -> ParseResult {
         parse::next_instruction(data)
     }
diff --git a/src/register.rs b/src/register.rs
index d895cdd..1696066 100644
--- a/src/register.rs
+++ b/src/register.rs
@@ -73,6 +73,7 @@ impl Flag {
 }
 
 impl Registers {
+    #[must_use]
     pub fn new() -> Self {
         Self::default()
     }
@@ -101,10 +102,11 @@ impl Registers {
     /// Get the a flag in the flag register.
     /// It is suggested that you use the constants in the `flag` module when calling this method.
     /// Will only ever be zero or one
+    #[must_use]
+    #[allow(clippy::missing_panics_doc)]
     pub fn get_flag_bit(&self, flag: Flag) -> u8 {
         let pos = flag.get_regiter_pos();
-        // There are only 8 flag registers. If you use anything other than the constants,
-        // you may deserve what you get.
+        // programming error if this happens
         assert!(pos < 8);
 
         (self.flags & (1 << pos)) >> pos
@@ -112,6 +114,9 @@ impl Registers {
 
     /// Set a flag register bit (at position `pos`) to the given value.
     /// This will only pay attention to the first bit, so only zero or one should be passed
+    ///
+    /// # Panics
+    /// Panics if flag is of a value that isn't 0 or 1
     pub fn set_flag_bit(&mut self, flag: Flag, value: u8) {
         assert!(value <= 1);
 
@@ -123,6 +128,7 @@ impl Registers {
         self.flags |= bit << pos;
     }
 
+    #[must_use]
     pub fn get_single_8bit_register(&self, register: SingleEightBit) -> u8 {
         match register {
             SingleEightBit::A => self.a,
@@ -151,6 +157,7 @@ impl Registers {
 
     /// Get the value of a 16 bit register, whether it's natively a 16 bit register or a combination of
     /// 8 bit registers
+    #[must_use]
     pub fn get_16bit_register(&self, register: SixteenBit) -> u16 {
         match register {
             SixteenBit::Single(single) => self.get_single_16bit_register(single),
@@ -159,6 +166,7 @@ impl Registers {
     }
 
     /// Get the value of a single 16 bit register (i.e. a natively 16 bit register)
+    #[must_use]
     pub fn get_single_16bit_register(&self, register: SingleSixteenBit) -> u16 {
         match register {
             SingleSixteenBit::StackPointer => self.stack_pointer,
@@ -167,6 +175,7 @@ impl Registers {
     }
 
     /// Get the value of combined single 16 bit register (i.e. a combination of two 8 bit registers)
+    #[must_use]
     pub fn get_combined_register(&self, registers: Combined) -> u16 {
         let (left_register, right_register) = self.get_register_values_for_combined(registers);
         let mut res = 0_u16;