diff --git a/rtgui/histogrampanel.cc b/rtgui/histogrampanel.cc
index 821f6f0be..b804218f5 100644
--- a/rtgui/histogrampanel.cc
+++ b/rtgui/histogrampanel.cc
@@ -1197,7 +1197,7 @@ void HistogramArea::update(
                 break;
             case ScopeType::PARADE:
             case ScopeType::WAVEFORM: {
-                MyWriterLock wave_lock(wave_mutex);
+                MYWRITERLOCK(wave_lock, wave_mutex)
                 waveform_scale = waveformScale;
                 rwave = waveformRed;
                 gwave = waveformGreen;
@@ -1330,7 +1330,7 @@ void HistogramArea::updateBackBuffer ()
 
     cr->unset_dash();
 
-    MyReaderLock wave_lock(wave_mutex);
+    MYREADERLOCK(wave_lock, wave_mutex)
     if (valid && (scopeType == ScopeType::HISTOGRAM || scopeType == ScopeType::HISTOGRAM_RAW)) {
         bool rawMode = scopeType == ScopeType::HISTOGRAM_RAW;
 
@@ -1447,7 +1447,7 @@ void HistogramArea::updateBackBuffer ()
     } else if (scopeType == ScopeType::VECTORSCOPE_HC || scopeType == ScopeType::VECTORSCOPE_HS) {
         drawVectorscope(cr, w, h);
     }
-    wave_lock.release();
+    MYREADERLOCK_RELEASE(wave_lock);
 
     // Draw the frame's border
     style->render_frame(cr, 0, 0, surface->get_width(), surface->get_height());
diff --git a/rtgui/threadutils.cc b/rtgui/threadutils.cc
index f747510d3..9bc9cf35d 100644
--- a/rtgui/threadutils.cc
+++ b/rtgui/threadutils.cc
@@ -17,7 +17,6 @@
  *  along with RawTherapee.  If not, see <https://www.gnu.org/licenses/>.
  */
 #include "threadutils.h"
-#include <glibmm/threads.h>
 
 #include <csignal>
 #include <iostream>
@@ -28,6 +27,8 @@
 
 #if STRICT_MUTEX && !NDEBUG
 
+MyMutex::MyMutex() : locked(false) {}
+
 void MyMutex::checkLock ()
 {
     if (locked) {
@@ -62,13 +63,18 @@ void MyMutex::checkUnlock ()
 
 #if !TRACE_MYRWMUTEX
 
+MyRWMutex::MyRWMutex() :
+    writerCount(0),
+    readerCount(0)
+{}
+
 void MyReaderLock::acquire ()
 {
     if (locked) {
         return;
     }
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     if (mutex.writerCount == 0) {
         // There's no writer operating, we can increment the writer count which will lock writers.
@@ -77,7 +83,7 @@ void MyReaderLock::acquire ()
         // The writer count is non null, but a reader can be the owner of the writer lock,
         // which will be the case if the reader count is not zero too.
         while (mutex.writerCount != 0) {
-            mutex.cond.wait(mutex.mutex);
+            mutex.cond.wait (lock);
         }
 
         // Then, we can increment the writer count.
@@ -96,7 +102,7 @@ void MyReaderLock::release ()
         return;
     }
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     // decrement the writer number first...
     --mutex.readerCount;
@@ -106,7 +112,7 @@ void MyReaderLock::release ()
         --mutex.writerCount;
 
         // ...and signal the next waiting reader/writer that it's free
-        mutex.cond.notify_one();  // notify_all ?
+        mutex.cond.notify_all ();
     }
 
     locked = false;
@@ -118,11 +124,11 @@ void MyWriterLock::acquire ()
         return;
     }
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     // The writer count is not zero, so we have to wait for it to be zero again...
     while (mutex.writerCount != 0) {
-        mutex.cond.wait (mutex.mutex);
+        mutex.cond.wait (lock);
     }
 
     // ...then we can increment the writer count.
@@ -137,12 +143,12 @@ void MyWriterLock::release ()
         return;
     }
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     // Decrement the writer number first...
     if (--mutex.writerCount == 0) {
-        // ...and if the writer count is zero again, we can wake up the next writer or reader.
-        mutex.cond.notify_one();  // notify_all ?
+        // ...and if the writer count is zero again, we wake up all of the waiting writer or reader.
+        mutex.cond.notify_all ();
     }
 
     locked = false;
@@ -155,13 +161,20 @@ namespace
 
 std::ostream& trace (const char* file, int line)
 {
-    const auto currentThread = Glib::Threads::Thread::self ();
+    const auto currentThread = std::this_thread::get_id();
 
     return std::cout << currentThread << ":" << file << ":" << line << ": ";
 }
 
 }
 
+MyRWMutex::MyRWMutex() :
+    lastWriterFile(nullptr),
+    lastWriterLine(0),
+    writerCount(0),
+    readerCount(0)
+{}
+
 void MyReaderLock::acquire (const char* file, int line)
 {
     if (locked) {
@@ -171,7 +184,7 @@ void MyReaderLock::acquire (const char* file, int line)
 
     trace (file, line) << "Acquiring MyReaderLock..." << std::endl;
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     if (mutex.writerCount == 0) {
         // There's no writer operating, we can increment the writer count which will lock writers.
@@ -185,13 +198,13 @@ void MyReaderLock::acquire (const char* file, int line)
                                << "\tLast writer file: " << mutex.lastWriterFile << std::endl
                                << "\tLast writer line: " << mutex.lastWriterLine << std::endl;
 
-            mutex.cond.wait(mutex.mutex);
+            mutex.cond.wait (lock);
         }
 
         // Then, we can increment the writer count.
         ++mutex.writerCount;
 
-        mutex.ownerThread = Glib::Threads::Thread::self ();
+        mutex.ownerThread = std::this_thread::get_id ();
         mutex.lastWriterFile = file;
         mutex.lastWriterLine = line;
     }
@@ -212,7 +225,7 @@ void MyReaderLock::release (const char* file, int line)
 
     trace (file, line) << "Releasing MyReaderLock..." << std::endl;
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     // decrement the writer number first...
     --mutex.readerCount;
@@ -222,9 +235,9 @@ void MyReaderLock::release (const char* file, int line)
         --mutex.writerCount;
 
         // ...and signal the next waiting reader/writer that it's free
-        mutex.cond.notify_one();  // notify_all ?
+        mutex.cond.notify_all ();
 
-        mutex.ownerThread = nullptr;
+        mutex.ownerThread = std::thread::id();
         mutex.lastWriterFile = "";
         mutex.lastWriterLine = 0;
     }
@@ -242,7 +255,7 @@ void MyWriterLock::acquire (const char* file, int line)
 
     trace (file, line) << "Acquiring MyWriterLock..." << std::endl;
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     // The writer count is not zero, so we have to wait for it to be zero again...
     while (mutex.writerCount != 0) {
@@ -251,13 +264,13 @@ void MyWriterLock::acquire (const char* file, int line)
                            << "\tLast writer file: " << mutex.lastWriterFile << std::endl
                            << "\tLast writer line: " << mutex.lastWriterLine << std::endl;
 
-        mutex.cond.wait (mutex.mutex);
+        mutex.cond.wait (lock);
     }
 
     // ...then we can increment the writer count.
     ++mutex.writerCount;
 
-    mutex.ownerThread = Glib::Threads::Thread::self ();
+    mutex.ownerThread = std::this_thread::get_id ();
     mutex.lastWriterFile = file;
     mutex.lastWriterLine = line;
 
@@ -274,14 +287,14 @@ void MyWriterLock::release (const char* file, int line)
 
     trace (file, line) << "Releasing MyWriterLock..." << std::endl;
 
-    std::lock_guard<std::mutex> lock (mutex.mutex);
+    std::unique_lock<std::mutex> lock (mutex.mutex);
 
     // Decrement the writer number first...
     if (--mutex.writerCount == 0) {
-        // ...and if the writer count is zero again, we can wake up the next writer or reader.
-        mutex.cond.notify_one();  // notify_all ?
+        // ...and if the writer count is zero again, we wake up all of the waiting writer or reader.
+        mutex.cond.notify_all ();
 
-        mutex.ownerThread = nullptr;
+        mutex.ownerThread = std::thread::id();
         mutex.lastWriterFile = "";
         mutex.lastWriterLine = 0;
     }
diff --git a/rtgui/threadutils.h b/rtgui/threadutils.h
index cdf093b52..401660b93 100644
--- a/rtgui/threadutils.h
+++ b/rtgui/threadutils.h
@@ -25,6 +25,7 @@
 //#define STRICT_MUTEX 1
 
 #include <mutex>
+#include <thread>
 #include <condition_variable>
 #include "../rtengine/noncopyable.h"
 
@@ -54,8 +55,10 @@ public:
     void unlock ();
 
 #if STRICT_MUTEX && !NDEBUG
+    MyMutex();
+
 private:
-    bool locked = false;
+    bool locked;
     void checkLock ();
     void checkUnlock ();
 #endif
@@ -88,18 +91,20 @@ public:
     friend class MyReaderLock;
     friend class MyWriterLock;
 
+    MyRWMutex();
+
 private:
-    std::mutex mutex;
-    std::condition_variable_any cond;
-
-    std::size_t writerCount = 0;
-    std::size_t readerCount = 0;
-
 #if TRACE_MYRWMUTEX
-    Glib::Threads::Thread* ownerThread = nullptr;
-    const char* lastWriterFile = "";
-    int lastWriterLine = 0;
+    std::thread::id ownerThread;
+    const char* lastWriterFile;
+    int lastWriterLine;
 #endif
+
+    std::mutex mutex;
+    std::condition_variable cond;
+
+    std::size_t writerCount;
+    std::size_t readerCount;
 };
 
 /**
diff --git a/rtgui/thumbimageupdater.cc b/rtgui/thumbimageupdater.cc
index 65958797e..d196fdca5 100644
--- a/rtgui/thumbimageupdater.cc
+++ b/rtgui/thumbimageupdater.cc
@@ -85,7 +85,7 @@ public:
 
     Glib::ThreadPool* threadPool_;
 
-    // Need to be a std::mutex because used in a std::condition_variable_any object...
+    // Need to be a std::mutex because used in a std::condition_variable object...
     // This is the only exceptions along with GThreadMutex (guiutils.cc), MyMutex is used everywhere else
     std::mutex mutex_;
 
@@ -95,7 +95,7 @@ public:
 
     bool inactive_waiting_;
 
-    std::condition_variable_any inactive_;
+    std::condition_variable inactive_;
 
     void
     processNextJob()
@@ -169,7 +169,7 @@ public:
             std::lock_guard<std::mutex> lock(mutex_);
             if (inactive_waiting_) {
                 inactive_waiting_ = false;
-                inactive_.notify_one();  // notify_all ?
+                inactive_.notify_all();
             }
         }
     }
@@ -246,9 +246,9 @@ void ThumbImageUpdater::removeJobs(ThumbImageUpdateListener* listener)
     while ( impl_->active_ != 0 ) {
         DEBUG("waiting for running jobs1");
         {
-            std::lock_guard<std::mutex> lock(impl_->mutex_);
+            std::unique_lock<std::mutex> lock(impl_->mutex_);
             impl_->inactive_waiting_ = true;
-            impl_->inactive_.wait(impl_->mutex_);
+            impl_->inactive_.wait(lock);
         }
     }
 }
@@ -266,9 +266,9 @@ void ThumbImageUpdater::removeAllJobs()
     while ( impl_->active_ != 0 ) {
         DEBUG("waiting for running jobs2");
         {
-            std::lock_guard<std::mutex> lock(impl_->mutex_);
+            std::unique_lock<std::mutex> lock(impl_->mutex_);
             impl_->inactive_waiting_ = true;
-            impl_->inactive_.wait(impl_->mutex_);
+            impl_->inactive_.wait(lock);
         }
     }
 }