diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 1ad4daf6..173f2646 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -3371,6 +3371,7 @@ Stefan Hofmann <stefan.hofmann@t-online.de>
  for suggesting to implement jumping between errors while replaying a recording
  for adding vdrrootdir and incdir to vdr.pc
  for fixing some typos in the translation files
+ for adding 1 to Utf8BufSize() for worst case
 
 Stefan Blochberger <Stefan.Blochberger@gmx.de>
  for suggesting to automatically display the progress display whenever replay of a
diff --git a/HISTORY b/HISTORY
index 00fe4b3b..c47a51b1 100644
--- a/HISTORY
+++ b/HISTORY
@@ -10049,3 +10049,4 @@ Video Disk Recorder Revision History
   schedule.
 - Fixed a possible deadlock when canceling an editing process.
 - Checking for VPS control is now limited to local timers.
+- Added 1 to Utf8BufSize() for worst case (thanks to Stefan Hofmann).
diff --git a/tools.h b/tools.h
index 8a83a1f3..3b9b7df3 100644
--- a/tools.h
+++ b/tools.h
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: tools.h 5.10 2024/09/01 20:43:40 kls Exp $
+ * $Id: tools.h 5.11 2025/01/13 13:18:42 kls Exp $
  */
 
 #ifndef __TOOLS_H
@@ -140,7 +140,7 @@ int Utf8FromArray(const uint *a, char *s, int Size, int Max = -1);
 // When allocating buffer space, make sure we reserve enough space to hold
 // a string in UTF-8 representation:
 
-#define Utf8BufSize(s) ((s) * 4)
+#define Utf8BufSize(s) ((s) * 4 + 1)
 
 // The following macros automatically use the correct versions of the character
 // class functions: