diff --git a/cl/_testlibgo/_atomic/in.go b/cl/_testlibgo/atomic/in.go
similarity index 100%
rename from cl/_testlibgo/_atomic/in.go
rename to cl/_testlibgo/atomic/in.go
diff --git a/internal/build/build.go b/internal/build/build.go
index c8744e42..552a71f1 100644
--- a/internal/build/build.go
+++ b/internal/build/build.go
@@ -413,7 +413,8 @@ type aPackage struct {
 type none struct{}
 
 var hasAltPkg = map[string]none{
-	"math": {},
+	"math":        {},
+	"sync/atomic": {},
 }
 
 type importer = func(pkgPath string) *packages.Package
diff --git a/internal/lib/sync/atomic/atomic.go b/internal/lib/sync/atomic/atomic.go
new file mode 100644
index 00000000..f62c5356
--- /dev/null
+++ b/internal/lib/sync/atomic/atomic.go
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package atomic
+
+// llgo:skip init
+import (
+	_ "unsafe"
+)
+
+const (
+	LLGoPackage = true
+)
+
+//go:linkname cAddInt64 llgo.atomicAdd
+func cAddInt64(addr *int64, delta int64) (old int64)
+
+func AddInt64(addr *int64, delta int64) (new int64) {
+	return cAddInt64(addr, delta) + delta
+}