diff --git a/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt b/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt
index d76395e20..61b63f48d 100644
--- a/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt
+++ b/app/src/main/java/io/legado/app/model/webBook/BookChapterList.kt
@@ -11,6 +11,7 @@ import io.legado.app.model.NoStackTraceException
 import io.legado.app.model.TocEmptyException
 import io.legado.app.model.analyzeRule.AnalyzeRule
 import io.legado.app.model.analyzeRule.AnalyzeUrl
+import io.legado.app.utils.isTrue
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.async
@@ -23,8 +24,6 @@ import splitties.init.appCtx
  */
 object BookChapterList {
 
-    private val falseRegex = "\\s*(?i)(null|false|0)\\s*".toRegex()
-
     suspend fun analyzeChapterList(
         scope: CoroutineScope,
         bookSource: BookSource,
@@ -188,7 +187,7 @@ object BookChapterList {
                 bookChapter.tag = analyzeRule.getString(upTimeRule)
                 val isVolume = analyzeRule.getString(isVolumeRule)
                 bookChapter.isVolume = false
-                if (isVolume.isNotEmpty() && !isVolume.matches(falseRegex)) {
+                if (isVolume.isTrue()) {
                     bookChapter.isVolume = true
                 }
                 if (bookChapter.url.isEmpty()) {
@@ -203,10 +202,10 @@ object BookChapterList {
                 if (bookChapter.title.isNotEmpty()) {
                     val isVip = analyzeRule.getString(vipRule)
                     val isPay = analyzeRule.getString(payRule)
-                    if (isVip.isNotEmpty() && !isVip.matches(falseRegex)) {
+                    if (isVip.isTrue()) {
                         bookChapter.isVip = true
                     }
-                    if (isPay.isNotEmpty() && !isPay.matches(falseRegex)) {
+                    if (isPay.isTrue()) {
                         bookChapter.isPay = true
                     }
                     chapterList.add(bookChapter)
diff --git a/app/src/main/java/io/legado/app/utils/StringExtensions.kt b/app/src/main/java/io/legado/app/utils/StringExtensions.kt
index d026812e8..341c8a417 100644
--- a/app/src/main/java/io/legado/app/utils/StringExtensions.kt
+++ b/app/src/main/java/io/legado/app/utils/StringExtensions.kt
@@ -53,6 +53,13 @@ fun String?.isXml(): Boolean =
         str.startsWith("<") && str.endsWith(">")
     } ?: false
 
+fun String?.isTrue(nullIsTrue: Boolean = false): Boolean {
+    if (this.isNullOrBlank() || this == "null") {
+        return nullIsTrue
+    }
+    return this.matches("\\s*(?i)(true|ok|yes|1)\\s*".toRegex())
+}
+
 fun String.splitNotBlank(vararg delimiter: String): Array<String> = run {
     this.split(*delimiter).map { it.trim() }.filterNot { it.isBlank() }.toTypedArray()
 }