diff --git a/cranelift-backend/src/lib.rs b/cranelift-backend/src/lib.rs
index bf4d052..5f56c5c 100644
--- a/cranelift-backend/src/lib.rs
+++ b/cranelift-backend/src/lib.rs
@@ -334,6 +334,8 @@ impl FuncBuilder<'_, '_> {
                     self.bl.ins().stack_store(v, slot, offset);
                     offset += align as i32;
                 }
+                self.values[arg as usize] =
+                    Some(Ok(self.bl.ins().stack_addr(cir::types::I64, slot, 0)))
             } else {
                 let loc = arg_vals.take(..abi_meta.arg_count).unwrap();
                 debug_assert_eq!(loc.len(), 1);
@@ -516,6 +518,8 @@ impl FuncBuilder<'_, '_> {
                 Err(self.block_of(block))
             }
             Kind::Call { func, unreachable, args } => {
+                assert_ne!(func, hbty::Func::ECA, "@eca is not supported");
+
                 if unreachable {
                     todo!()
                 } else {
diff --git a/smh.hb b/smh.hb
new file mode 100644
index 0000000..8273941
--- /dev/null
+++ b/smh.hb
@@ -0,0 +1,31 @@
+ResultInner := fn($T: type, $E: type): type return union {ok: T, err: E}
+
+Result := fn($T: type, $E: type): type return struct {
+	inner: ResultInner(T, E),
+	is_ok: bool,
+
+	$ok := fn(k: T): Self return .(.{ok: k}, true)
+	$err := fn(k: E): Self return .(.{err: k}, false)
+	$unwrap := fn(self: Self): T return self.expect("Panic: Unwrap on Error Variant.\0".ptr)
+	$unwrap_unchecked := fn(self: Self): T return self.inner.ok
+	unwrap_or := fn(self: Self, v: T): T if self.is_ok return self.inner.ok else return v
+	unwrap_or_else := fn(self: Self, $F: type): T if self.is_ok return self.inner.ok else return F(self.inner.err)
+	expect := fn(self: Self, msg: ^u8): T if self.is_ok return self.inner.ok else {
+		@eca(0, msg)
+		die
+	}
+}
+
+SomeError := enum {
+	SkillIssue,
+}
+
+div := fn(a: uint, b: uint): Result(uint, SomeError) {
+	if b != 0 return Result(uint, SomeError).ok(a / b)
+	return Result(uint, SomeError).err(.SkillIssue)
+}
+
+main := fn(): uint {
+	a := div(100, 0)
+	return a.expect("goof\0".ptr)
+}