diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp
index 9b37225..0a452e9 100644
--- a/libc/bionic/pthread_mutex.cpp
+++ b/libc/bionic/pthread_mutex.cpp
@@ -182,7 +182,12 @@
         return 0;
     }
     if (ret == EBUSY) {
-        ScopedTrace trace("Contending for pthread mutex");
+        char trace_msg[64];
+        const pid_t owner = atomic_load_explicit(&mutex.owner_tid, memory_order_relaxed)
+                & FUTEX_TID_MASK;
+        snprintf(trace_msg, sizeof(trace_msg),
+                 "Contending for pthread mutex owned by tid: %d", owner);
+        ScopedTrace trace(trace_msg);
         ret = -__futex_pi_lock_ex(&mutex.owner_tid, mutex.shared, use_realtime_clock, abs_timeout);
     }
     return ret;