diff --git a/hphp/runtime/base/hphp_array.cpp b/hphp/runtime/base/hphp_array.cpp
index 040afaa62..6538fc39f 100644
--- a/hphp/runtime/base/hphp_array.cpp
+++ b/hphp/runtime/base/hphp_array.cpp
@@ -1397,7 +1397,7 @@ ArrayData* HphpArray::nvNew(TypedValue*& ret, bool copy) {
 // nvGetKey does not touch out->_count, so can be used
 // for inner or outer cells.
 void HphpArray::NvGetKeyVec(const ArrayData* ad, TypedValue* out, ssize_t pos) {
-  auto a = asVector(ad);
+  DEBUG_ONLY auto a = asVector(ad);
   assert(pos != ArrayData::invalid_index);
   assert(!isTombstone(a->m_data[pos].data.m_type));
   out->m_data.num = pos;
diff --git a/hphp/runtime/vm/jit/translator-x64.cpp b/hphp/runtime/vm/jit/translator-x64.cpp
index a3dffb0b8..500e76197 100644
--- a/hphp/runtime/vm/jit/translator-x64.cpp
+++ b/hphp/runtime/vm/jit/translator-x64.cpp
@@ -59,6 +59,7 @@
 #include "hphp/util/timer.h"
 #include "hphp/util/trace.h"
 #include "hphp/util/meta.h"
+#include "hphp/util/process.h"
 #include "hphp/util/util.h"
 #include "hphp/util/repo_schema.h"
 #include "hphp/util/cycles.h"
@@ -3824,7 +3825,7 @@ TranslatorX64::requestExit() {
   }
   TRACE_MOD(txlease, 2, "%" PRIx64 " write lease stats: %15" PRId64
             " kept, %15" PRId64 " grabbed\n",
-            pthread_self(), s_writeLease.m_hintKept,
+            Process::GetThreadIdForTrace(), s_writeLease.m_hintKept,
             s_writeLease.m_hintGrabbed);
   PendQ::drain();
   Treadmill::finishRequest(g_vmContext->m_currentThreadIdx);
diff --git a/hphp/runtime/vm/jit/write-lease.cpp b/hphp/runtime/vm/jit/write-lease.cpp
index 6809bbc74..3a81a3128 100644
--- a/hphp/runtime/vm/jit/write-lease.cpp
+++ b/hphp/runtime/vm/jit/write-lease.cpp
@@ -14,6 +14,7 @@
    +----------------------------------------------------------------------+
 */
 #include "hphp/runtime/vm/jit/write-lease.h"
+#include "hphp/util/process.h"
 #include "hphp/util/timer.h"
 #include "hphp/runtime/vm/bytecode.h"
 #include "hphp/runtime/vm/jit/translator.h"
@@ -77,7 +78,7 @@ bool Lease::acquire(bool blocking /* = false */ ) {
             pthread_mutex_lock(&m_lock) :
             pthread_mutex_trylock(&m_lock))) {
     TRACE(4, "thr%" PRIx64 ": acquired lease, called by %p,%p\n",
-          pthread_self(), __builtin_return_address(0),
+          Process::GetThreadIdForTrace(), __builtin_return_address(0),
           __builtin_return_address(1));
     if (debug) {
       pushRank(RankWriteLease);
@@ -86,7 +87,7 @@ bool Lease::acquire(bool blocking /* = false */ ) {
         TRACE(3,
               "thr%" PRIx64 ": acquired hinted lease"
               ", expired %" PRId64 "us ago\n",
-              pthread_self(), -expireDiff);
+              Process::GetThreadIdForTrace(), -expireDiff);
       } else if (expire != 0 && m_owner == pthread_self()) {
         m_hintKept++;
       }
@@ -100,7 +101,7 @@ bool Lease::acquire(bool blocking /* = false */ ) {
   }
   if (blocking) {
     TRACE(3, "thr%" PRIx64 ": failed to acquired lease in blocking mode\n",
-          pthread_self());
+          Process::GetThreadIdForTrace());
   }
   return false;
 }
@@ -108,7 +109,7 @@ bool Lease::acquire(bool blocking /* = false */ ) {
 void Lease::drop(int64_t hintExpireDelay) {
   assert(amOwner());
   TRACE(4, "thr%" PRIx64 ": dropping lease, called by %p,%p\n",
-        pthread_self(), __builtin_return_address(0),
+        Process::GetThreadIdForTrace(), __builtin_return_address(0),
         __builtin_return_address(1));
   if (debug) {
     popRank(RankWriteLease);
diff --git a/hphp/util/process.h b/hphp/util/process.h
index 686c22387..8b7f1cc7d 100644
--- a/hphp/util/process.h
+++ b/hphp/util/process.h
@@ -115,6 +115,21 @@ public:
     return pthread_self();
   }
 
+  /**
+   * Current thread's identifier.
+   */
+  static uint64_t GetThreadIdForTrace() {
+    // For tracing purposes this just needs to be unique, pthread_t is not
+    // portable but even if it's a pointer to a struct like on OSX this will
+    // produce a unique value. If we support platforms where this isn't the
+    // case we will need to revisit this.
+#ifdef __linux__
+    return pthread_self();
+#else
+    return (uint64_t)pthread_self();
+#endif
+  }
+
   /*
    * Thread's process identifier.
    */
diff --git a/hphp/util/rank.cpp b/hphp/util/rank.cpp
index 7bc370841..80f615e39 100644
--- a/hphp/util/rank.cpp
+++ b/hphp/util/rank.cpp
@@ -18,6 +18,7 @@
 
 #include "hphp/util/base.h"
 #include "hphp/util/mutex.h"
+#include "hphp/util/process.h"
 
 namespace HPHP {
 #ifdef DEBUG
@@ -44,10 +45,10 @@ void checkRank(Rank r) {
       if (r == RankLeaf) {
         fprintf(stderr,
                 "Rank violation in thr%" PRIx64 "! leaf lock from leaf rank; ",
-                pthread_self());
+                Process::GetThreadIdForTrace());
       } else {
         fprintf(stderr, "Rank violation in thr%" PRIx64 "! lock of rank %d; ",
-                pthread_self(), r);
+                Process::GetThreadIdForTrace(), r);
       }
       fprintf(stderr, "held locks:\n");
       for (int i = tl_curRankDepth - 1; i >= 0; --i) {