diff --git a/lldb/source/Plugins/Process/Utility/HistoryThread.cpp b/lldb/source/Plugins/Process/Utility/HistoryThread.cpp
index 590bb0162c8a..206b8290c5fd 100644
--- a/lldb/source/Plugins/Process/Utility/HistoryThread.cpp
+++ b/lldb/source/Plugins/Process/Utility/HistoryThread.cpp
@@ -39,7 +39,7 @@ HistoryThread::HistoryThread (lldb_private::Process &process,
         m_originating_unique_thread_id (tid),
         m_queue_id (LLDB_INVALID_QUEUE_ID)
 {
-    m_unwinder_ap.reset (new HistoryUnwind (*this, pcs, stop_id, stop_id_is_valid));
+    m_unwinder_ap.reset (new HistoryUnwind (*this, pcs, stop_id_is_valid));
     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_OBJECT));
     if (log)
         log->Printf ("%p HistoryThread::HistoryThread",
diff --git a/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp b/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
index f809ebedcfc8..14afcbee0b49 100644
--- a/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
+++ b/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
@@ -24,11 +24,9 @@ using namespace lldb_private;
 
 HistoryUnwind::HistoryUnwind (Thread &thread,
                               std::vector<lldb::addr_t> pcs,
-                              uint32_t stop_id,
                               bool stop_id_is_valid) :
         Unwind (thread),
         m_pcs (pcs),
-        m_stop_id (stop_id),
         m_stop_id_is_valid (stop_id_is_valid)
 {
 }
diff --git a/lldb/source/Plugins/Process/Utility/HistoryUnwind.h b/lldb/source/Plugins/Process/Utility/HistoryUnwind.h
index 0661b8028608..733f93e1ff87 100644
--- a/lldb/source/Plugins/Process/Utility/HistoryUnwind.h
+++ b/lldb/source/Plugins/Process/Utility/HistoryUnwind.h
@@ -21,7 +21,7 @@ namespace lldb_private {
 class HistoryUnwind : public lldb_private::Unwind
 {
 public:
-    HistoryUnwind (Thread &thread, std::vector<lldb::addr_t> pcs, uint32_t stop_id, bool stop_id_is_valid);
+    HistoryUnwind (Thread &thread, std::vector<lldb::addr_t> pcs, bool stop_id_is_valid);
 
     virtual ~HistoryUnwind ();
 
@@ -42,7 +42,6 @@ protected:
 private:
 
     std::vector<lldb::addr_t>   m_pcs;
-    uint32_t                    m_stop_id;
     bool                        m_stop_id_is_valid;
 };