diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index af0bc06f..646112fb 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -1236,6 +1236,7 @@ Marco Schl
  for fixing handling EPG data for time shifted events
  for fixing detecting short channel names for "Kabel Deutschland"
  for reporting that the FATALERRNO macro needs to check for a non-zero errno value
+ for reporting missing mutex locks in cCiMenu::Abort() and cCiEnquiry::Abort()
 
 Jürgen Schmitz <j.schmitz@web.de>
  for reporting a bug in displaying the current channel when switching via the SVDRP
diff --git a/HISTORY b/HISTORY
index e976868d..b8111c34 100644
--- a/HISTORY
+++ b/HISTORY
@@ -3886,7 +3886,7 @@ Video Disk Recorder Revision History
 - The 'sub-title' and 'bottom text' in the CAM menu can now consist of several lines.
 - Improved the CAM enquiry menu.
 
-2005-10-14: Version 1.3.35
+2005-10-30: Version 1.3.35
 
 - Updated 'sources.conf' (thanks to Philip Prindeville).
 - Now using daemon() instead of fork() to run VDR in daemon mode (thanks to
@@ -3903,3 +3903,5 @@ Video Disk Recorder Revision History
   (thanks to Peter Bieringer).
 - Updated the Danish OSD texts (thanks to Mogens Elneff).
 - Updated the Estonian OSD texts (thanks to Arthur Konovalov).
+- Added missing mutex locks to cCiMenu::Abort() and cCiEnquiry::Abort() (reported
+  by Marco Schlüßler).
diff --git a/ci.c b/ci.c
index 9e86c613..542e318e 100644
--- a/ci.c
+++ b/ci.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: ci.c 1.36 2005/10/03 12:58:22 kls Exp $
+ * $Id: ci.c 1.37 2005/10/30 10:24:38 kls Exp $
  */
 
 #include "ci.h"
@@ -1267,6 +1267,7 @@ bool cCiMenu::Cancel(void)
 
 bool cCiMenu::Abort(void)
 {
+  cMutexLock MutexLock(&mutex);
   return mmi && mmi->SendCloseMMI();
 }
 
@@ -1301,6 +1302,7 @@ bool cCiEnquiry::Cancel(void)
 
 bool cCiEnquiry::Abort(void)
 {
+  cMutexLock MutexLock(&mutex);
   return mmi && mmi->SendCloseMMI();
 }