diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0808ea7de..426229e9f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -191,6 +191,8 @@ list( APPEND SOURCES
       Prefs.h
       Printing.cpp
       Printing.h
+      Profiler.cpp
+      Profiler.h
       Project.cpp
       Project.h
       ProjectAudioIO.cpp
diff --git a/src/FileFormats.cpp b/src/FileFormats.cpp
index 156079444..7f086caf5 100644
--- a/src/FileFormats.cpp
+++ b/src/FileFormats.cpp
@@ -320,6 +320,8 @@ static OSType sf_header_mactype(int format)
 
 #endif // __WXMAC__
 
+//std::mutex libSndFileMutex;
+
 int SFFileCloser::operator() (SNDFILE *sf) const
 {
    auto err = SFCall<int>(sf_close, sf);
diff --git a/src/FileFormats.h b/src/FileFormats.h
index 0bdac41ac..4d7696079 100644
--- a/src/FileFormats.h
+++ b/src/FileFormats.h
@@ -15,6 +15,7 @@
 
 #include "audacity/Types.h"
 
+//#include <mutex>
 #include "MemoryX.h"
 
 #include "sndfile.h"
@@ -105,9 +106,16 @@ extern FileExtensions sf_get_all_extensions();
 
 wxString sf_normalize_name(const char *name);
 
+
+// This function wrapper uses a mutex to serialize calls to the SndFile library.
+// PRL: Keeping this in a comment, but with Unitary, the only remaining uses
+// of libsndfile should be in import/export and so are on the main thread only
+//extern std::mutex libSndFileMutex;
+
 template<typename R, typename F, typename... Args>
 inline R SFCall(F fun, Args&&... args)
 {
+   //std::lock_guard<std::mutex> guard{ libSndFileMutex };
    return fun(std::forward<Args>(args)...);
 }
 
diff --git a/src/Profiler.cpp b/src/Profiler.cpp
index 6c106d6b6..76c1b3c92 100644
--- a/src/Profiler.cpp
+++ b/src/Profiler.cpp
@@ -63,20 +63,18 @@ Profiler::~Profiler()
 ///start the task timer.
 void Profiler::Begin(const char* fileName, int lineNum, const char* taskDescription)
 {
-   mTasksMutex.Lock();
+   std::lock_guard<std::mutex> guard{ mTasksMutex };
    GetOrCreateTaskProfile(fileName,lineNum)->Begin(fileName,lineNum,taskDescription);
-   mTasksMutex.Unlock();
 }
 
 ///end the task timer.
 void Profiler::End(const char* fileName, int lineNum, const char* taskDescription)
 {
-   mTasksMutex.Lock();
+   std::lock_guard<std::mutex> guard{ mTasksMutex };
    TaskProfile* tp;
    tp=GetTaskProfileByDescription(taskDescription);
    if(tp)
       tp->End(fileName,lineNum,taskDescription);
-   mTasksMutex.Unlock();
 }
 
 ///Gets the singleton instance
diff --git a/src/Profiler.h b/src/Profiler.h
index 149820396..698cbbb5b 100644
--- a/src/Profiler.h
+++ b/src/Profiler.h
@@ -26,8 +26,10 @@ but it will probably work fine if you use it on a high level.
 
 #ifndef __AUDACITY_PROFILER__
 #define __AUDACITY_PROFILER__
+#include <mutex>
 #include <vector>
 #include <time.h>
+#include "MemoryX.h"
 
 
 #define BEGIN_TASK_PROFILING(TASK_DESCRIPTION) Profiler::Instance()->Begin(__FILE__,__LINE__,TASK_DESCRIPTION)
@@ -59,6 +61,8 @@ class Profiler
 
    //List of current Task to do.
    std::vector<std::unique_ptr<TaskProfile>> mTasks;
+   //mutex for above variable
+   std::mutex mTasksMutex;
 
 };
 
diff --git a/src/Project.cpp b/src/Project.cpp
index 4e624fa4a..9e08a5329 100644
--- a/src/Project.cpp
+++ b/src/Project.cpp
@@ -47,6 +47,7 @@ auto AllProjects::rend() const -> const_reverse_iterator
 
 auto AllProjects::Remove( AudacityProject &project ) -> value_type
 {
+   std::lock_guard<std::mutex> guard{ Mutex() };
    auto start = begin(), finish = end(), iter = std::find_if(
       start, finish,
       [&]( const value_type &ptr ){ return ptr.get() == &project; }
@@ -60,6 +61,7 @@ auto AllProjects::Remove( AudacityProject &project ) -> value_type
 
 void AllProjects::Add( const value_type &pProject )
 {
+   std::lock_guard<std::mutex> guard{ Mutex() };
    gAudacityProjects.push_back( pProject );
 }
 
@@ -85,6 +87,12 @@ bool AllProjects::Close( bool force )
    return true;
 }
 
+std::mutex &AllProjects::Mutex()
+{
+   static std::mutex theMutex;
+   return theMutex;
+}
+
 int AudacityProject::mProjectCounter=0;// global counter.
 
 /* Define Global Variables */
diff --git a/src/Project.h b/src/Project.h
index 047858fa2..a386aba39 100644
--- a/src/Project.h
+++ b/src/Project.h
@@ -16,6 +16,7 @@
 #include "ClientData.h" // to inherit
 
 #include <memory>
+#include <mutex>
 #include <wx/weakref.h> // member variable
 #include <wx/window.h> // MSVC wants this
 
@@ -63,6 +64,10 @@ public:
    // This invalidates iterators
    void Add( const value_type &pProject );
 
+   /// In case you must iterate in a non-main thread, use this to prevent
+   /// changes in the set of open projects
+   static std::mutex &Mutex();
+
    // Return true if all projects do close (always so if force == true)
    // But if return is false, that means the user cancelled close of at least
    // one un-saved project.