diff --git a/src/BuiltinFn.zig b/src/BuiltinFn.zig
index a5d15554afbe408282a5c5777c908b30ac8d6b9a..8df36c3cf03d3f96ebcbddc54bfb713e8756541d 100644
--- a/src/BuiltinFn.zig
+++ b/src/BuiltinFn.zig
@@ -129,7 +129,7 @@ pub const list = list: {
             "@alignCast",
             .{
                 .tag = .align_cast,
-                .param_count = 1,
+                .param_count = 2,
             },
         },
         .{