diff --git a/app/src/main/java/io/legado/app/data/entities/BaseSource.kt b/app/src/main/java/io/legado/app/data/entities/BaseSource.kt
index 05e1a6ec3..0c4c186f7 100644
--- a/app/src/main/java/io/legado/app/data/entities/BaseSource.kt
+++ b/app/src/main/java/io/legado/app/data/entities/BaseSource.kt
@@ -59,7 +59,6 @@ interface BaseSource : JsExtensions {
      * 解析header规则
      */
     fun getHeaderMap(hasLoginHeader: Boolean = false) = HashMap<String, String>().apply {
-        this[AppConst.UA_NAME] = AppConfig.userAgent
         header?.let {
             GSON.fromJsonObject<Map<String, String>>(
                 when {
@@ -73,6 +72,9 @@ interface BaseSource : JsExtensions {
                 putAll(map)
             }
         }
+        if (!has(AppConst.UA_NAME, true)) {
+            put(AppConst.UA_NAME, AppConfig.userAgent)
+        }
         if (hasLoginHeader) {
             getLoginHeaderMap()?.let {
                 putAll(it)
diff --git a/app/src/main/java/io/legado/app/utils/MapExtensions.kt b/app/src/main/java/io/legado/app/utils/MapExtensions.kt
new file mode 100644
index 000000000..520a2b132
--- /dev/null
+++ b/app/src/main/java/io/legado/app/utils/MapExtensions.kt
@@ -0,0 +1,19 @@
+package io.legado.app.utils
+
+fun HashMap<String, *>.has(key: String, ignoreCase: Boolean = false): Boolean {
+    for (item in this) {
+        if (key.equals(item.key, ignoreCase)) {
+            return true
+        }
+    }
+    return false
+}
+
+fun HashMap<String, *>.get(key: String, ignoreCase: Boolean = false): Any? {
+    for (item in this) {
+        if (key.equals(item.key, ignoreCase)) {
+            return item.value
+        }
+    }
+    return null
+}
\ No newline at end of file