diff --git a/src/interpreter/computer.rs b/src/interpreter/computer.rs
index f114573..d62ee60 100644
--- a/src/interpreter/computer.rs
+++ b/src/interpreter/computer.rs
@@ -56,47 +56,57 @@ impl Computer {
         let mut argv_ptrs = Vec::new();
 
         let envs = Vec::from(["PATH=/usr:/usr/bin".to_string()]);
-        let mut env_ptrs = Vec::new();
 
         // Padding
-        let total_len_argv: usize = argv.iter().map(|i| i.len()).sum();
-        let total_len_env: usize = envs.iter().map(|i| i.len()).sum();
+        let total_len_argv = argv.iter().map(|i| i.len()).sum::<usize>();
+        let total_len_env = 1  // padding for env string null delimeter
+            + envs.iter().map(|i| i.len()  // len of single env entry
+                + 1 // padding for each env null delimeter
+            ).sum::<usize>();
 
         if total_len_argv + total_len_env % 2 != 0 {
+            log::debug!("Pushing aligment byte at top of stack.");
             self.push_stack(ImmediateOperand::Byte(0))?;
         }
 
         // Write env
+        self.push_stack(ImmediateOperand::Byte(0))?; // env null delimeter
         for env in envs.iter() {
+            log::debug!("Adding env {env} to stack");
             for b in env.chars().rev() {
+                log::debug!("{}", b);
                 self.push_stack(ImmediateOperand::Byte(b as u8))?;
             }
-            env_ptrs.push(self.regs.sp);
         }
+        let env_head = self.regs.sp;
 
         // Write argv
         for arg in argv.iter() {
-            // self.push_stack(ImmediateOperand::Byte(0))?;
+            log::debug!("Adding arg {arg} to stack");
+            self.push_stack(ImmediateOperand::Byte(0))?;
             for b in arg.chars().rev() {
+                log::debug!("{}", b);
                 self.push_stack(ImmediateOperand::Byte(b as u8))?;
             }
             argv_ptrs.push(self.regs.sp);
         }
 
-        // add env ptrs
-        for addr in env_ptrs {
-            self.push_stack(addr.into())?;
-        }
+        self.push_stack(ImmediateOperand::Word(0))?;
+
+        // add env ptr
+        log::debug!("Pushing env ptr");
+        self.push_stack(env_head.into())?;
 
-        // delimiter
         self.push_stack(ImmediateOperand::Word(0))?;
 
         // add argv ptrs
         for addr in argv_ptrs {
+            log::debug!("Pushing argv ptr {addr:#04x}");
             self.push_stack(addr.into())?;
         }
 
         // add argc
+        log::debug!("Pushing argc");
         self.push_stack(ImmediateOperand::Word(argc as Word))?;
 
         Ok(())
@@ -104,7 +114,11 @@ impl Computer {
 
     /// Decrement stack pointer and write `val` onto the stack.
     pub fn push_stack(&mut self, val: ImmediateOperand) -> Result<(), InterpreterError> {
-        self.regs.push_sp();
+        self.regs.sp = self.regs.sp.wrapping_sub(match val {
+            ImmediateOperand::Byte(_) => 1,
+            ImmediateOperand::Word(_) => 2,
+        });
+        log::debug!("writing at sp: {:#04x}", self.regs.sp);
         self.memory.write_raw(
             self.mem_addr(
                 ImmediateOperand::from(self.regs.sp).into(),
@@ -120,7 +134,7 @@ impl Computer {
             ImmediateOperand::from(self.regs.sp).into(),
             &crate::register::SegmentRegister::SS,
         ))?;
-        self.regs.pop_sp();
+        self.regs.sp = self.regs.sp.wrapping_add(2);
         Ok(word)
     }
 
diff --git a/src/interpreter/register.rs b/src/interpreter/register.rs
index 675c33b..d00ac40 100644
--- a/src/interpreter/register.rs
+++ b/src/interpreter/register.rs
@@ -27,20 +27,6 @@ impl Register {
         }
     }
 
-    /// Decrement stack pointer
-    pub fn push_sp(&mut self) {
-        log::debug!("SP before push: {:04x}", self.sp);
-        self.sp = self.sp.wrapping_sub(2);
-        log::debug!("SP after push: {:04x}", self.sp);
-    }
-
-    /// Increment stack pointer
-    pub fn pop_sp(&mut self) {
-        log::debug!("SP before pop: {:04x}", self.sp);
-        self.sp = self.sp.wrapping_add(2);
-        log::debug!("SP after pop: {:04x}", self.sp);
-    }
-
     /// Read value from a [`crate::register::Register`].
     pub fn read(&self, reg: crate::register::Register) -> ImmediateOperand {
         match reg {