diff --git a/logback-core/src/main/java/ch/qos/logback/core/FileAppender.java b/logback-core/src/main/java/ch/qos/logback/core/FileAppender.java
index 2c92a3538b..952befca32 100644
--- a/logback-core/src/main/java/ch/qos/logback/core/FileAppender.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/FileAppender.java
@@ -280,6 +280,7 @@ private void safeWriteBytes(byte[] byteArray) {
                 fileChannel.position(size);
             }
             writeByteArrayToOutputStreamWithPossibleFlush(byteArray);
+            updateByteCount(byteArray);
         } catch (IOException e) {
             // Mainly to catch FileLockInterruptionExceptions (see LOGBACK-875)
             resilientFOS.postIOFailure(e);