diff --git a/app/src/main/java/cn/airnan/a2fair/ui/tokens/AddTokenBottomSheet.kt b/app/src/main/java/cn/airnan/a2fair/ui/tokens/AddTokenBottomSheet.kt
index 729eff8..d9ee300 100644
--- a/app/src/main/java/cn/airnan/a2fair/ui/tokens/AddTokenBottomSheet.kt
+++ b/app/src/main/java/cn/airnan/a2fair/ui/tokens/AddTokenBottomSheet.kt
@@ -373,8 +373,14 @@ fun CameraPreview(onScan: (String) -> Unit) {
 
 class ZxingAnalyzer(private val onScan: (String) -> Unit) : ImageAnalysis.Analyzer {
     private val reader = MultiFormatReader()
+    @Volatile
+    private var scanned = false
 
     override fun analyze(image: ImageProxy) {
+        if (scanned) {
+            image.close()
+            return
+        }
         val buffer = image.planes[0].buffer
         val data = ByteArray(buffer.capacity())
         buffer.get(data)
@@ -395,6 +401,7 @@ class ZxingAnalyzer(private val onScan: (String) -> Unit) : ImageAnalysis.Analyz
             val result = reader.decode(binaryBitmap)
             val text = result.text
             if (text.startsWith("otpauth://")) {
+                scanned = true
                 onScan(text)
             }
         } catch (e: NotFoundException) {