diff --git a/baselib.ml b/baselib.ml
index 2110b03..610e304 100644
--- a/baselib.ml
+++ b/baselib.ml
@@ -2,11 +2,19 @@ open Ast
 open Mips
 module Env = Map.Make (String)
 
-let _types_ = Env.of_seq (List.to_seq [ "%add", Func_t (Int_t, [ Int_t; Int_t ]) ])
+let _types_ =
+  Env.of_seq
+    (List.to_seq
+       [ "%add", Func_t (Int_t, [ Int_t; Int_t ])
+       ; "%mul", Func_t (Int_t, [ Int_t; Int_t ])
+       ])
+;;
 
 let builtins =
   List.fold_left
     (fun env (fn, impl) -> Env.add fn impl env)
     Env.empty
-    [ "%add", [ Lw (T0, Mem (SP, 0)); Lw (T1, Mem (SP, 4)); Add (V0, T0, T1) ] ]
+    [ "%add", [ Lw (T0, Mem (SP, 0)); Lw (T1, Mem (SP, 4)); Add (V0, T0, T1) ]
+    ; "%mul", [ Lw (T0, Mem (SP, 0)); Lw (T1, Mem (SP, 4)); Mul (V0, T0, T1) ]
+    ]
 ;;
diff --git a/lexer.mll b/lexer.mll
index cd3c9d8..5294e76 100644
--- a/lexer.mll
+++ b/lexer.mll
@@ -21,7 +21,8 @@ rule token = parse
 | bool as b     { Lbool (bool_of_string b) }
 | '='           { Lassign }
 | ';'           { Lsc }
-| '+'           { Ladd}
+| '+'           { Ladd }
+| '*'           { Lmul }
 | ident as i    { Lvar i }
 | '#'           { comment lexbuf }
 | _ as c        { raise (Error c) }
diff --git a/parser.mly b/parser.mly
index 9848b7b..74df4af 100644
--- a/parser.mly
+++ b/parser.mly
@@ -8,9 +8,9 @@
 %token <Ast.type_t> Ltype
 %token <string> Lvar
 %token Lend Lassign Lsc Lreturn
-%token Ladd
+%token Ladd Lmul
 
-%left Ladd
+%left Ladd Lmul
 
 %start prog
 
@@ -49,4 +49,7 @@ expr:
   | a = expr ; Ladd ; b = expr {
     Call { func = "%add" ; args = [ a ; b ] ; pos = $startpos($2) }
   }
+  | a = expr ; Lmul ; b = expr {
+    Call { func = "%mul" ; args = [ a ; b ] ; pos = $startpos($2) }
+  }
 ;
diff --git a/tests/10_add-mul.test b/tests/10_add-mul.test
new file mode 100644
index 0000000..1a7bbe7
--- /dev/null
+++ b/tests/10_add-mul.test
@@ -0,0 +1 @@
+int res = 13 * 100 + 12;
diff --git a/tests/10_add.test b/tests/10_add.test
deleted file mode 100644
index cffa17b..0000000
--- a/tests/10_add.test
+++ /dev/null
@@ -1 +0,0 @@
-int res = 1 + 1;