diff --git a/2016/12/Cargo.lock b/2016/12/Cargo.lock
new file mode 100644
index 0000000..41caa46
--- /dev/null
+++ b/2016/12/Cargo.lock
@@ -0,0 +1,105 @@
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+
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diff --git a/2016/12/Cargo.toml b/2016/12/Cargo.toml
new file mode 100644
index 0000000..1684a6a
--- /dev/null
+++ b/2016/12/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "12"
+version = "0.1.0"
+authors = ["logaritmisk <anders.e.olsson@gmail.com>"]
+
+[dependencies]
+lazy_static = "0.1"
+regex = "0.1"
diff --git a/2016/12/example.txt b/2016/12/example.txt
new file mode 100644
index 0000000..01a004b
--- /dev/null
+++ b/2016/12/example.txt
@@ -0,0 +1,6 @@
+cpy 41 a
+inc a
+inc a
+dec a
+jnz a 2
+dec a
diff --git a/2016/12/input.txt b/2016/12/input.txt
new file mode 100644
index 0000000..bb2a2ff
--- /dev/null
+++ b/2016/12/input.txt
@@ -0,0 +1,23 @@
+cpy 1 a
+cpy 1 b
+cpy 26 d
+jnz c 2
+jnz 1 5
+cpy 7 c
+inc d
+dec c
+jnz c -2
+cpy a c
+inc a
+dec b
+jnz b -2
+cpy c b
+dec d
+jnz d -6
+cpy 17 c
+cpy 18 d
+inc a
+dec d
+jnz d -2
+dec c
+jnz c -5
diff --git a/2016/12/src/main.rs b/2016/12/src/main.rs
new file mode 100644
index 0000000..441f0ad
--- /dev/null
+++ b/2016/12/src/main.rs
@@ -0,0 +1,182 @@
+#[macro_use] extern crate lazy_static;
+extern crate regex;
+
+use std::collections::HashMap;
+use std::str::FromStr;
+use std::io::{self, BufRead};
+
+use regex::Regex;
+
+
+type Register = String;
+type Value = i64;
+
+
+#[derive(Debug, PartialEq)]
+pub enum Input {
+    Value(Value),
+    Register(Register)
+}
+
+impl FromStr for Input {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Input, Self::Err> {
+        if let Ok(value) = s.parse::<Value>() {
+            return Ok(Input::Value(value));
+        }
+
+        if let Ok(register) = s.parse::<Register>() {
+            return Ok(Input::Register(register));
+        }
+
+        Err(())
+    }
+}
+
+
+#[derive(Debug, PartialEq)]
+pub enum Operation {
+    Cpy(Input, Register),
+    Inc(Register),
+    Dec(Register),
+    Jnz(Input, i64)
+}
+
+impl FromStr for Operation {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Operation, Self::Err> {
+        lazy_static! {
+            static ref CPY: Regex = Regex::new(r"^cpy ([a-z]|-?\d+) ([a-z])$").unwrap();
+            static ref INC: Regex = Regex::new(r"^inc ([a-z])$").unwrap();
+            static ref DEC: Regex = Regex::new(r"^dec ([a-z])$").unwrap();
+            static ref JNZ: Regex = Regex::new(r"^jnz ([a-z]|-?\d+) (-?\d+)$").unwrap();
+        }
+
+        if let Some(caps) = CPY.captures(s) {
+            let input = caps.at(1).unwrap().parse::<Input>().unwrap();
+            let register = caps.at(2).unwrap().parse::<Register>().unwrap();
+
+            return Ok(Operation::Cpy(input, register));
+        }
+
+        if let Some(caps) = INC.captures(s) {
+            let register = caps.at(1).unwrap().parse::<Register>().unwrap();
+
+            return Ok(Operation::Inc(register));
+        }
+
+        if let Some(caps) = DEC.captures(s) {
+            let register = caps.at(1).unwrap().parse::<Register>().unwrap();
+
+            return Ok(Operation::Dec(register));
+        }
+
+        if let Some(caps) = JNZ.captures(s) {
+            let input = caps.at(1).unwrap().parse::<Input>().unwrap();
+            let delta = caps.at(2).unwrap().parse::<i64>().unwrap();
+
+            return Ok(Operation::Jnz(input, delta));
+        }
+
+
+        Err(())
+    }
+}
+
+
+#[derive(Debug)]
+pub struct CPU {
+    pc: usize,
+    reg: HashMap<Register, Value>,
+}
+
+impl CPU {
+    pub fn new() -> Self {
+        CPU {
+            pc: 0,
+            reg: HashMap::new()
+        }
+    }
+
+    pub fn execute(&mut self, input: &Vec<Operation>) {
+        loop {
+            if self.pc >= input.len() {
+                break;
+            }
+
+            match &input[self.pc] {
+                &Operation::Cpy(ref value, ref register) => {
+                    let input = match value {
+                        &Input::Value(value) => {
+                            value
+                        }
+                        &Input::Register(ref register) => {
+                            *self.reg.entry(register.clone()).or_insert(0)
+                        }
+                    };
+
+                    *self.reg.entry(register.clone()).or_insert(0) = input;
+
+                    self.pc += 1;
+                }
+                &Operation::Inc(ref register) => {
+                    *self.reg.entry(register.clone()).or_insert(0) += 1;
+
+                    self.pc += 1;
+                }
+                &Operation::Dec(ref register) => {
+                    *self.reg.entry(register.clone()).or_insert(0) -= 1;
+
+                    self.pc += 1;
+                }
+                &Operation::Jnz(ref value, delta) => {
+                    let input = match value {
+                        &Input::Value(value) => {
+                            value
+                        }
+                        &Input::Register(ref register) => {
+                            *self.reg.entry(register.clone()).or_insert(0)
+                        }
+                    };
+
+                    if input != 0 {
+                        self.pc = ((self.pc as i64) + delta) as usize;
+                    } else {
+                        self.pc += 1;
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+fn main() {
+    let stdin = io::stdin();
+
+    let operations = stdin.lock().lines()
+        .filter_map(|x| x.ok())
+        .filter_map(|line| line.parse::<Operation>().ok())
+        .collect::<Vec<_>>();
+
+    let mut cpu = CPU::new();
+
+    cpu.reg.entry("c".to_owned()).or_insert(1);
+
+    cpu.execute(&operations);
+
+    println!("{:#?}", cpu);
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_jnz() {
+        assert_eq!(Ok(Operation::Jnz(Input::Register("c".to_owned()), -2)), "jnz c -2".parse::<Operation>());
+    }
+}