diff --git a/xorriso/text_io.c b/xorriso/text_io.c
index bb7c77ce..c0e33a2b 100644
--- a/xorriso/text_io.c
+++ b/xorriso/text_io.c
@@ -888,8 +888,9 @@ static int Xorriso_write_to_msglist(struct XorrisO *xorriso,
  struct Xorriso_lsT *msglist;
 
  ret= Xorriso_lock_outlists(xorriso, 0);
- if(ret > 0)
-   locked= 1;
+ if(ret <= 0)
+   goto ex;
+ locked= 1;
  msglist= *xorriso_msglist;
  ret= Xorriso_lst_append_binary(&msglist, text, strlen(text) + 1, 0);
  if(ret <= 0) {
@@ -1174,9 +1175,12 @@ int Xorriso_push_outlists(struct XorrisO *xorriso, int *stack_handle,
  int ret, locked= 0;
 
  ret= Xorriso_lock_outlists(xorriso, 0);
- if(ret > 0)
-   locked= 1;
+ if(ret <= 0)
+   goto ex;
+ locked= 1;
  if(xorriso->msglist_stackfill + 1 >= Xorriso_max_outlist_stacK) {
+   Xorriso_unlock_outlists(xorriso, 0);
+   locked= 0;
    Xorriso_msgs_submit(xorriso, 0,
                 "Overflow of message output redirection stack", 0, "FATAL", 0);
    ret= -1; goto ex;
@@ -1215,12 +1219,15 @@ int Xorriso_fetch_outlists(struct XorrisO *xorriso, int stack_handle,
    flag|= 3;
 
  ret= Xorriso_lock_outlists(xorriso, 0);
- if(ret > 0)
-   locked= 1;
+ if(ret <= 0)
+   goto ex;
+ locked= 1;
 
  if(stack_handle == -1)
    stack_handle= xorriso->msglist_stackfill - 1;
  if(stack_handle < 0 || stack_handle >= xorriso->msglist_stackfill) {
+   Xorriso_unlock_outlists(xorriso, 0);
+   locked= 0;
    Xorriso_msgs_submit(xorriso, 0,
                 "Program error: Wrong message output redirection stack handle",
                 0, "FATAL", 0);
@@ -1304,12 +1311,15 @@ int Xorriso_pull_outlists(struct XorrisO *xorriso, int stack_handle,
  int i, ret, locked= 0;
 
  ret= Xorriso_lock_outlists(xorriso, 0);
- if(ret > 0)
-   locked= 1;
+ if(ret <= 0)
+   goto ex;
+ locked= 1;
 
  if(stack_handle == -1)
    stack_handle= xorriso->msglist_stackfill - 1;
  if(stack_handle < 0 || stack_handle >= xorriso->msglist_stackfill) {
+   Xorriso_unlock_outlists(xorriso, 0);
+   locked= 0;
    Xorriso_msgs_submit(xorriso, 0,
                 "Program error: Wrong message output redirection stack handle",
                 0, "FATAL", 0);
@@ -1442,7 +1452,7 @@ int Xorriso_process_msg_lists(struct XorrisO *xorriso,
 static void *Xorriso_msg_watcher(void *state_pt)
 {
  struct XorrisO *xorriso;
- int ret, u_wait= 25000, line_count, sleep_thresh= 20;
+ int ret, u_wait= 25000, line_count, sleep_thresh= 20, lock_failure= 0;
  struct Xorriso_lsT *result_list= NULL, *info_list= NULL;
  static int debug_sev= 0;
 
@@ -1464,8 +1474,12 @@ static void *Xorriso_msg_watcher(void *state_pt)
    if(xorriso->msg_watcher_state == 3)
  break;
 
-   Xorriso_obtain_lock(xorriso, &(xorriso->msgw_fetch_lock),
-                       "message watcher fetch operation", 1);
+   ret= Xorriso_obtain_lock(xorriso, &(xorriso->msgw_fetch_lock),
+                            "message watcher fetch operation", 1);
+   if(ret <= 0) {
+     lock_failure= 1;
+ break;
+   }
    xorriso->msgw_msg_pending= 1;
    ret= Xorriso_fetch_outlists(xorriso, -1, &result_list, &info_list, 3);
    if(ret > 0) {
@@ -1495,7 +1509,8 @@ static void *Xorriso_msg_watcher(void *state_pt)
  }
  if(xorriso->msgw_info_handler != NULL &&
     debug_sev < xorriso->report_about_severity &&
-    debug_sev < xorriso->abort_on_severity)
+    debug_sev < xorriso->abort_on_severity &&
+    !lock_failure)
    (*xorriso->msgw_info_handler)(xorriso,
                      "xorriso : DEBUG : Concurrent message watcher ended\n");
  xorriso->msg_watcher_state= 0;
@@ -1631,8 +1646,15 @@ int Xorriso_stop_msg_watcher(struct XorrisO *xorriso, int flag)
    usleep(u_wait);
  }
 
- Xorriso_obtain_lock(xorriso, &(xorriso->msgw_fetch_lock),
-                     "message watcher fetch operation", 1);
+ ret= Xorriso_obtain_lock(xorriso, &(xorriso->msgw_fetch_lock),
+                          "message watcher fetch operation", 1);
+ if(ret <= 0) {
+   Xorriso_msgs_submit(xorriso, 0,
+           "Cannot obtain mutex lock for managing concurrent message watcher",
+           ret, "FATAL", 0);
+   ret= -1;
+   goto ex;
+ }
  xorriso->msgw_msg_pending= 1;
  ret= Xorriso_pull_outlists(xorriso, xorriso->msgw_stack_handle,
                             &result_list, &info_list, 0);
diff --git a/xorriso/xorriso_timestamp.h b/xorriso/xorriso_timestamp.h
index 03988e66..41ab77e9 100644
--- a/xorriso/xorriso_timestamp.h
+++ b/xorriso/xorriso_timestamp.h
@@ -1 +1 @@
-#define Xorriso_timestamP "2015.11.13.202241"
+#define Xorriso_timestamP "2015.11.15.153822"