1 files changed, 2 insertions, 2 deletions
diff --git a/rts/Task.c b/rts/Task.c
index 3cfe6e1769..5c6d3cdf44 100644
--- a/rts/Task.c
+++ b/rts/Task.c
@@ -565,8 +565,8 @@ printAllTasks(void)
                 debugBelch("on capability %d, ", task->cap->no);
             }
             if (task->incall->tso) {
-              debugBelch("bound to thread %lu",
-                         (unsigned long)task->incall->tso->id);
+              debugBelch("bound to thread %" FMT_StgThreadID,
+                         task->incall->tso->id);
             } else {
                 debugBelch("worker");
             }