diff --git a/NEWS.md b/NEWS.md
index 653d170f..ce26f9ad 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -17,6 +17,7 @@ Red Panda C++ Version 2.19
   - fix: "Run all problem cases" with project is not correctly handled.
   - fix: When adding files to project and there'are duplicates, the warning info is not complete.
   - enhancement: Improve code completion suggestion for arrays.
+  - fix: File's real encoding is not correctly calculated when save it using system default encoding.
 
 Red Panda C++ Version 2.18
 
diff --git a/libs/qsynedit/qsynedit/document.cpp b/libs/qsynedit/qsynedit/document.cpp
index 4cfe2091..f64546cb 100644
--- a/libs/qsynedit/qsynedit/document.cpp
+++ b/libs/qsynedit/qsynedit/document.cpp
@@ -778,7 +778,7 @@ void Document::saveToFile(QFile &file, const QByteArray& encoding,
     }
     if (allAscii) {
         realEncoding = ENCODING_ASCII;
-    } else if (encoding == ENCODING_AUTO_DETECT) {
+    } else if (realEncoding == ENCODING_SYSTEM_DEFAULT) {
         if (QString(codec->name()).compare("System",Qt::CaseInsensitive)==0) {
             realEncoding = pCharsetInfoManager->getDefaultSystemEncoding();
         } else {