diff --git a/src/cc/builtin.c b/src/cc/builtin.c
index 01aa6da5c..da31260a5 100644
--- a/src/cc/builtin.c
+++ b/src/cc/builtin.c
@@ -253,8 +253,8 @@ static VReg *gen_alloca(Expr *expr) {
   assert(curfunc != NULL);
   Expr *size = args->data[0];
   const Token *token = size->token;
-  Expr *aligned_size = new_expr_bop(
-      EX_BITAND, &tySSize, token,
+  Expr *aligned_size = new_expr_int_bop(
+      EX_BITAND, token,
       new_expr_addsub(EX_ADD, token, make_cast(&tySSize, token, size, false),
                       new_expr_fixlit(&tySSize, token, stack_align - 1)),
       new_expr_fixlit(&tySSize, token, -stack_align));
diff --git a/src/wcc/gen_wasm.c b/src/wcc/gen_wasm.c
index 9f8d5beb8..49156204f 100644
--- a/src/wcc/gen_wasm.c
+++ b/src/wcc/gen_wasm.c
@@ -1961,11 +1961,11 @@ static void gen_alloca(Expr *expr, enum BuiltinFunctionPhase phase) {
   assert(curfunc != NULL);
   Expr *size = args->data[0];
   const Token *token = size->token;
-  Expr *aligned_size =
-      new_expr_bop(EX_BITAND, &tySSize, token,
-                   new_expr_addsub(EX_ADD, token, make_cast(&tySSize, token, size, false),
-                                   new_expr_fixlit(&tySSize, token, stack_align - 1)),
-                   new_expr_fixlit(&tySSize, token, -stack_align));
+  Expr *aligned_size = new_expr_int_bop(
+      EX_BITAND, token,
+      new_expr_addsub(EX_ADD, token, make_cast(&tySSize, token, size, false),
+                      new_expr_fixlit(&tySSize, token, stack_align - 1)),
+      new_expr_fixlit(&tySSize, token, -stack_align));
 
   Expr *spvar = get_sp_var();
   gen_expr_stmt(new_expr_bop(EX_ASSIGN, &tyVoid, NULL, spvar,