diff --git a/app/src/main/java/io/legado/app/model/webbook/SourceDebug.kt b/app/src/main/java/io/legado/app/model/webbook/SourceDebug.kt
index 511b499bf..de180529a 100644
--- a/app/src/main/java/io/legado/app/model/webbook/SourceDebug.kt
+++ b/app/src/main/java/io/legado/app/model/webbook/SourceDebug.kt
@@ -22,6 +22,7 @@ class SourceDebug(private val webBook: WebBook, callback: Callback) {
         private val DEBUG_TIME_FORMAT = SimpleDateFormat("[mm:ss.SSS]", Locale.getDefault())
         private val startTime: Long = System.currentTimeMillis()
 
+        @Synchronized
         fun printLog(
             sourceUrl: String?,
             state: Int,