diff --git a/src/scheduler.c b/src/scheduler.c
index fe9fb9a208ac6a1a0d816c9c42d921f697d0b345..cb55aff8ffce895c0d75bca41f0857b317d01157 100644
--- a/src/scheduler.c
+++ b/src/scheduler.c
@@ -1083,6 +1083,7 @@ struct task *scheduler_addtask(struct scheduler *s, enum task_types type,
 #ifdef SWIFT_DEBUG_TASKS
   t->rid = -1;
   t->qtic = 0;
+  t->nr_locks = 0;
 #endif
   t->tic = 0;
   t->toc = 0;
@@ -1583,6 +1584,7 @@ void scheduler_start(struct scheduler *s) {
 #ifdef SWIFT_DEBUG_TASKS
     s->tasks[i].rid = -1;
     s->tasks[i].qtic = 0;
+    s->tasks[i].nr_locks = 0;
 #endif
   }
 
diff --git a/src/task.c b/src/task.c
index 4a10e37ef432ec7be997e064b92d66ec5add3bd7..d62772ee64c4dff769b5ee7c1206ec893d8468cc 100644
--- a/src/task.c
+++ b/src/task.c
@@ -535,6 +535,11 @@ int task_lock(struct task *t) {
   MPI_Status stat;
 #endif
 
+#ifdef SWIFT_DEBUG_TASKS
+  /* One more attempt to lock this. */
+  t->nr_locks++;
+#endif
+
   switch (type) {
 
     /* Communication task? */
@@ -918,7 +923,7 @@ void task_dump_all(struct engine *e, int step) {
 
       /* Add some information to help with the plots and conversion of ticks to
        * seconds. */
-      fprintf(file_thread, " %03d 0 0 0 0 %lld %lld %lld %lld %lld 0 0 0 %lld\n",
+      fprintf(file_thread, " %03d 0 0 0 0 %lld %lld %lld %lld %lld 0 0 0 0 %lld\n",
               engine_rank, (long long int)e->tic_step,
               (long long int)e->toc_step, e->updates, e->g_updates,
               e->s_updates, cpufreq);
@@ -926,12 +931,13 @@ void task_dump_all(struct engine *e, int step) {
       for (int l = 0; l < e->sched.nr_tasks; l++) {
         if (!e->sched.tasks[l].implicit && e->sched.tasks[l].toc != 0) {
           fprintf(
-              file_thread, " %03i %i %i %i %i %lli %lli %lli %i %i %i %i %lli %i\n",
+              file_thread, " %03i %i %i %i %i %lli %lli %lli %zd %i %i %i %i %lli %i\n",
               engine_rank, e->sched.tasks[l].rid, e->sched.tasks[l].type,
               e->sched.tasks[l].subtype, (e->sched.tasks[l].cj == NULL),
               (long long int)e->sched.tasks[l].tic,
               (long long int)e->sched.tasks[l].toc,
               (long long int)e->sched.tasks[l].qtic,
+              e->sched.tasks[l].nr_locks,
               (e->sched.tasks[l].ci != NULL) ? e->sched.tasks[l].ci->hydro.count
                                              : 0,
               (e->sched.tasks[l].cj != NULL) ? e->sched.tasks[l].cj->hydro.count
@@ -960,19 +966,20 @@ void task_dump_all(struct engine *e, int step) {
 
   /* Add some information to help with the plots and conversion of ticks to
    * seconds. */
-  fprintf(file_thread, " %d %d %d %d %lld %lld %d %lld %lld %lld %d %lld\n",
+  fprintf(file_thread, " %d %d %d %d %lld %lld %d %d %lld %lld %lld %d %lld\n",
           -2, -1, -1, 1, (unsigned long long)e->tic_step,
-          (unsigned long long)e->toc_step, 0, e->updates, e->g_updates,
+          (unsigned long long)e->toc_step, 0, 0, e->updates, e->g_updates,
           e->s_updates, 0, cpufreq);
   for (int l = 0; l < e->sched.nr_tasks; l++) {
     if (!e->sched.tasks[l].implicit && e->sched.tasks[l].toc != 0) {
       fprintf(
-          file_thread, " %i %i %i %i %lli %lli %lli %i %i %i %i %i\n",
+          file_thread, " %i %i %i %i %lli %lli %lli %zi %i %i %i %i %i\n",
           e->sched.tasks[l].rid, e->sched.tasks[l].type,
           e->sched.tasks[l].subtype, (e->sched.tasks[l].cj == NULL),
           (unsigned long long)e->sched.tasks[l].tic,
           (unsigned long long)e->sched.tasks[l].toc,
           (unsigned long long)e->sched.tasks[l].qtic,
+          e->sched.tasks[l].nr_locks,
           (e->sched.tasks[l].ci == NULL) ? 0
                                          : e->sched.tasks[l].ci->hydro.count,
           (e->sched.tasks[l].cj == NULL) ? 0
diff --git a/src/task.h b/src/task.h
index 9a188e578d2e0d03c9d37af7ab54994abee2f4ac..75bd5fbecc58870920349c0458208dc64a0638da 100644
--- a/src/task.h
+++ b/src/task.h
@@ -220,6 +220,9 @@ struct task {
 
   /*! Time when task was queued. */
   ticks qtic;
+
+  /* How many attempts to lock task. */
+  size_t nr_locks;
 #endif
 
   /*! Start and end time of this task */
diff --git a/tools/task_plots/analyse_tasks.py b/tools/task_plots/analyse_tasks.py
index 0a7382fc5787cfcb0e870e0b63d717b167ca9843..9935834ead564bb479ec36b9f66794b1a98aee61 100755
--- a/tools/task_plots/analyse_tasks.py
+++ b/tools/task_plots/analyse_tasks.py
@@ -163,7 +163,7 @@ full_step = data[0, :]
 
 #  Do we have an MPI file?
 full_step = data[0, :]
-if full_step.size == 14:
+if full_step.size == 15:
     print("# MPI mode")
     mpimode = True
     nranks = int(max(data[:, 0])) + 1
diff --git a/tools/task_plots/plot_tasks.py b/tools/task_plots/plot_tasks.py
index 571d6a07630b3e9ec5c80e78bdd9f506a597b90d..dc91941879b549d2899bc7c4537a6b6b976b85f7 100755
--- a/tools/task_plots/plot_tasks.py
+++ b/tools/task_plots/plot_tasks.py
@@ -366,7 +366,7 @@ data = pl.loadtxt(infile)
 
 #  Do we have an MPI file?
 full_step = data[0, :]
-if full_step.size == 14:
+if full_step.size == 15:
     print("# MPI mode")
     mpimode = True
     if ranks == None: