diff --git a/xray/plugin.go b/xray/plugin.go
index 9c4a366..2382cac 100644
--- a/xray/plugin.go
+++ b/xray/plugin.go
@@ -1,7 +1,9 @@
 package xray
 
 import (
+	"reflect"
 	"runtime/debug"
+	"strings"
 	"sync"
 
 	"github.com/shogo82148/aws-xray-yasdk-go/xray/schema"
@@ -38,6 +40,8 @@ func getPlugins() []Plugin {
 	return plugins
 }
 
+var _ Plugin = (*xrayPlugin)(nil)
+
 // xrayPlugin injects information about X-Ray YA-SDK.
 type xrayPlugin struct {
 	sdkVersion string
@@ -69,10 +73,18 @@ func getVersion() string {
 	if !ok {
 		return Version
 	}
+
+	// get the package path of the sdk
+	typ := reflect.TypeOf(xrayPlugin{})
+	pkg := typ.PkgPath()
+
+	version := Version
+	depth := 0
 	for _, dep := range info.Deps {
-		if dep.Path == "github.com/shogo82148/aws-xray-yasdk-go" {
-			return dep.Version
+		// search the most specific module
+		if strings.HasPrefix(pkg, dep.Path) && len(dep.Path) > depth {
+			version = dep.Version
 		}
 	}
-	return Version
+	return version
 }
diff --git a/xray/plugin_test.go b/xray/plugin_test.go
new file mode 100644
index 0000000..e844b58
--- /dev/null
+++ b/xray/plugin_test.go
@@ -0,0 +1,25 @@
+package xray
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestAddPlugin(t *testing.T) {
+	before := len(getPlugins())
+
+	// test of races
+	const n = 10
+	var wg sync.WaitGroup
+	wg.Add(n)
+	for i := 0; i < n; i++ {
+		go AddPlugin(&xrayPlugin{})
+		go getPlugins()
+	}
+
+	after := len(getPlugins())
+
+	if after-before != n {
+		t.Errorf("unexpected plugin count: want %d, got %d", n, after-before)
+	}
+}