diff --git a/chibicc.h b/chibicc.h
index 10252c3..04e4eab 100644
--- a/chibicc.h
+++ b/chibicc.h
@@ -106,6 +106,7 @@ typedef enum {
   ND_ADDR,      // unary &
   ND_DEREF,     // unary *
   ND_NOT,       // !
+  ND_BITNOT,    // ~
   ND_RETURN,    // "return"
   ND_IF,        // "if"
   ND_FOR,       // "for" or "while"
diff --git a/codegen.c b/codegen.c
index 3664364..1cedc99 100644
--- a/codegen.c
+++ b/codegen.c
@@ -216,6 +216,10 @@ static void gen_expr(Node *node) {
     println("  sete %%al");
     println("  movzx %%al, %%rax");
     return;
+  case ND_BITNOT:
+    gen_expr(node->lhs);
+    println("  not %%rax");
+    return;
   case ND_FUNCALL: {
     int nargs = 0;
     for (Node *arg = node->args; arg; arg = arg->next) {
diff --git a/parse.c b/parse.c
index 98769e1..e17b528 100644
--- a/parse.c
+++ b/parse.c
@@ -888,7 +888,7 @@ static Node *cast(Token **rest, Token *tok) {
   return unary(rest, tok);
 }
 
-// unary = ("+" | "-" | "*" | "&" | "!") cast
+// unary = ("+" | "-" | "*" | "&" | "!" | "~") cast
 //       | ("++" | "--") unary
 //       | postfix
 static Node *unary(Token **rest, Token *tok) {
@@ -907,6 +907,9 @@ static Node *unary(Token **rest, Token *tok) {
   if (equal(tok, "!"))
     return new_unary(ND_NOT, cast(rest, tok->next), tok);
 
+  if (equal(tok, "~"))
+    return new_unary(ND_BITNOT, cast(rest, tok->next), tok);
+
   // Read ++i as i+=1
   if (equal(tok, "++"))
     return to_assign(new_add(unary(rest, tok->next), new_num(1, tok), tok));
diff --git a/test/arith.c b/test/arith.c
index 6de47ba..4719240 100644
--- a/test/arith.c
+++ b/test/arith.c
@@ -71,6 +71,9 @@ int main() {
   ASSERT(4, sizeof(!(char)0));
   ASSERT(4, sizeof(!(long)0));
 
+  ASSERT(-1, ~0);
+  ASSERT(0, ~-1);
+
   printf("OK\n");
   return 0;
 }
diff --git a/type.c b/type.c
index 341545d..18f4bfe 100644
--- a/type.c
+++ b/type.c
@@ -127,6 +127,9 @@ void add_type(Node *node) {
   case ND_NOT:
     node->ty = ty_int;
     return;
+  case ND_BITNOT:
+    node->ty = node->lhs->ty;
+    return;
   case ND_VAR:
     node->ty = node->var->ty;
     return;