diff --git a/src-self-hosted/Module.zig b/src-self-hosted/Module.zig
index da5e575587957b5e7910fd00b40b7351bbefde7f..5fc1f7d67e24d3d56edb685a7cdd1158919b5460 100644
--- a/src-self-hosted/Module.zig
+++ b/src-self-hosted/Module.zig
@@ -1534,7 +1534,12 @@ fn astGenBuiltinCall(self: *Module, scope: *Scope, call: *ast.Node.BuiltinCall)
             const arg_count: ?usize = if (positionals.fields[0].field_type == []*zir.Inst) null else positionals.fields.len;
             if (arg_count) |some| {
                 if (call.params_len != some) {
-                    return self.failTok(scope, call.builtin_token, "expected {} parameter, found {}", .{ some, call.params_len });
+                    return self.failTok(
+                        scope,
+                        call.builtin_token,
+                        "expected {} parameter{}, found {}",
+                        .{ some, if (some == 1) "" else "s", call.params_len },
+                    );
                 }
                 const params = call.params();
                 inline for (positionals.fields) |p, i| {
diff --git a/src-self-hosted/zir.zig b/src-self-hosted/zir.zig
index 92dbc66e2b9f928f9dca1dcfee5e3c0a93645ff1..7b77575f55ed0e5028999787570bf9f12beef0f3 100644
--- a/src-self-hosted/zir.zig
+++ b/src-self-hosted/zir.zig
@@ -290,6 +290,7 @@ pub const Inst = struct {
 
     pub const As = struct {
         pub const base_tag = Tag.as;
+        pub const builtin_name = "@as";
         base: Inst,
 
         positionals: struct {