diff --git a/stages/lisp0/lisp.asm b/stages/lisp0/lisp.asm
index 8caf651..b8a0b72 100644
--- a/stages/lisp0/lisp.asm
+++ b/stages/lisp0/lisp.asm
@@ -3,11 +3,16 @@
 section .bss
     buf resb 0x100
     align 8,db 0
-    atoms times 2 resb 8
+    atoms times 3 resb 8
     env resq 1
 ;;
 section .text
 
+global get_env
+get_env:
+    mov rax, qword [rel env]
+    ret
+
     ;; converts char $dil to a digit with radix $rsi, returning it in $edx. $al is set to 1 if the char is a valid digit, and 0 otherwise.
 to_digit:
     lea eax, [rsi - 2]
@@ -103,11 +108,44 @@ extern dealloc
 
     ATOM_QUOTE equ 0
     ATOM_TRUE equ 1
+    ATOM_PLUS equ 2
 
-    QUOTE_STR db "quote", 0
+    QUOTE_STR db "quote"
     QUOTE_STR_LEN equ $ - QUOTE_STR
-    TRUE_STR db "t", 0
+    TRUE_STR db "t"
     TRUE_STR_LEN equ $ - TRUE_STR
+    PLUS_STR db "+"
+    PLUS_STR_LEN equ $ - PLUS_STR
+
+    ;; add $rdi and $rsi
+p_add:
+    call obj_tag_part
+    cmp al, OBJ_NUM
+    jne .invalid
+    call obj_addr_part
+    mov rdx, qword [rax + 8]    ; num1
+    mov rdi, rsi
+    call obj_tag_part
+    cmp al, OBJ_NUM
+    jne .invalid
+    call obj_addr_part
+    mov rax, qword [rax + 8]    ; num2
+    add rax, rdx                ; num1 + num2
+    push rax
+    mov rdi, 16                 ; struct { refcount: usize, value: i64 }
+    mov rsi, 8
+    call alloc
+    mov [rax], 1           ; refcount = 1
+    pop rdx
+    mov qword [rax + 8], rdx     ; value = sum
+    mov rdi, rax
+    mov rsi, OBJ_NUM
+    call obj_set_tag
+    ret
+.invalid:
+    xor rdi, rdi
+    call panic_abort
+
 
 global init_env
 init_env:
@@ -120,36 +158,76 @@ init_env:
     mov rdi, rax                ; $rdi = (t . t)
     lea rsi, [rel nil]
     call cons                   ; ((t . t) . nil)
+    push rax
+
+    lea rdi, [rel atoms]
+    mov rdi, [rdi + ATOM_PLUS * 8] ; get the "+" atom
+    lea rsi, [rel p_add]
+    call make_prim_pair          ; ("+" . p_add)
+    mov rdi, rax
+    mov rsi, qword [rsp]
+    call cons
+    mov qword [rsp], rax
+    
+
+    pop rax
     mov qword [rel env], rax             ; env = ((t . t) . nil)
     ret
 
 global init_atoms
-init_atoms:
+;; makes a (atom . prim) cons cell out of an atom symbol and a primitive function pointer
+make_prim_pair:
+    push rdi
+    push rsi
     mov rdi, 16
     mov rsi, 8
     call alloc
     mov dword [rax], 1          ; refcount = 1
-    mov dword [rax + 4], QUOTE_STR_LEN ; length of "quote
-    lea rcx, [rel QUOTE_STR]
-    mov qword [rax + 8], rcx           ; pointer to "quote"
+    pop rsi
+    mov qword [rax + 8], rsi     ; pointer to primitive function
+    mov rdi, rax
+    mov rsi, OBJ_PRIM
+    call obj_set_tag
+    mov rsi, rax
+    pop rdi
+    call obj_inc_ref
+    call cons
+    ret
+    
+make_atom:
+    push rdi
+    push rsi
+    mov rdi, 16
+    mov rsi, 8
+    call alloc
+    pop rsi
+    pop rdi
+    mov dword [rax], 1          ; refcount = 1
+    mov dword [rax + 4], esi     ; length of string
+    mov qword [rax + 8], rdi     ; pointer to string
     mov rdi, rax
     mov rsi, OBJ_ATOM
     call obj_set_tag
+    ret
+
+init_atoms:
+    mov rdi, QUOTE_STR
+    mov rsi, QUOTE_STR_LEN
+    call make_atom
     lea rcx, [rel atoms]
     mov qword [rcx], rax                ; atoms[0] = "quote"
 
-    mov rdi, 16
-    mov rsi, 8
-    call alloc
-    mov dword [rax], 1          ; refcount = 1
-    mov dword [rax + 4], TRUE_STR_LEN ; length of "t"
-    lea rcx, [rel TRUE_STR]
-    mov qword [rax + 8], rcx           ; pointer to "t"
-    mov rdi, rax
-    mov rsi, OBJ_ATOM
-    call obj_set_tag
+    mov rdi, TRUE_STR
+    mov rsi, TRUE_STR_LEN
+    call make_atom
     lea rcx, [rel atoms]
-    mov qword [rcx + 8], rax            ; atoms[1] = "t"
+    mov qword [rcx + 8], rax                ; atoms[1] = "t"
+
+    mov rdi, PLUS_STR
+    mov rsi, PLUS_STR_LEN
+    call make_atom
+    lea rcx, [rel atoms]
+    mov qword [rcx + 16], rax                ; atoms[2] = "+"
     ret
     
 
@@ -184,18 +262,19 @@ obj_eq:
     mov qword [rsp + 8], rax
     mov rdi, qword [rsp]    ; restore obj1
     call obj_addr_part
-    mov rdx, dword [rax + 4]    ; len1
+    movzx rdx, dword [rax + 4]    ; len1
     mov rcx, qword [rsp + 8]    ; ptr2
-    mov rbx, dword [rcx + 4]        ; len2
+    movzx rbx, dword [rcx + 4]        ; len2
     cmp rdx, rbx
     jne .not_equal
     mov rdx, qword [rax + 8]    ; ptr1
     mov rsi, qword [rcx + 8]    ; ptr2
     cmp rdx, rsi
     je .equal
-    mov rdi, rdx                ; $rdi = ptr1
-    mov rsi, rsi                ; $rsi = ptr2
-    mov rdx, rbx                ; $rdx = len1 = len2
+    mov rdi, rdx
+    mov rdx, rsi
+    mov rsi, rbx
+    mov rcx, rbx
     call strcmp
     test al, al
     je .equal
@@ -831,8 +910,8 @@ reduce:
     call is_nil
     test al, al
     mov rax, qword [rsp]        ; eval_env
-    xchg qword [rsp + 8], rax    ; 
-    cmovz qword [rsp + 8], rdi  ; env = closure_env == nil ? eval_env : closure_env
+    cmovz rax, rdi              ; env = closure_env == nil ? eval_env : closure_env
+    xchg qword [rsp + 8], rax   ;
     mov rdi, rax                ; restore closure
     call get_car
     mov rdi, rax                ; (params . body)
diff --git a/stages/lisp0/lisp.rs b/stages/lisp0/lisp.rs
index a962df0..347e492 100644
--- a/stages/lisp0/lisp.rs
+++ b/stages/lisp0/lisp.rs
@@ -2,6 +2,8 @@ unsafe extern "C" {
     fn init_atoms();
     fn parse_next_token(src: *mut Source<'_>) -> Object;
     fn init_env() -> Object;
+    fn eval(expr: Object, env: Object) -> Object;
+    fn get_env() -> Object;
 }
 
 struct Source<'a> {
@@ -130,8 +132,10 @@ fn test_parse_list() {
     let env = unsafe { *ENV_INIT };
     println!("env: {:?}", env);
 
-    let input = b"('a 3 4 5)";
+    let input = b"(+ (+ 1 2) 3)";
     let mut src = Source::from(&input[..]);
     let sexp = unsafe { parse_next_token(&raw mut src) };
     println!("{:?}", sexp);
+    let result = unsafe { eval(sexp, get_env()) };
+    println!("{:?}", result);
 }