diff --git a/src/lib/image/MovieFFMpeg/MovieFFMpeg.cpp b/src/lib/image/MovieFFMpeg/MovieFFMpeg.cpp
index 99969a1a5..febc326e1 100644
--- a/src/lib/image/MovieFFMpeg/MovieFFMpeg.cpp
+++ b/src/lib/image/MovieFFMpeg/MovieFFMpeg.cpp
@@ -31,6 +31,7 @@
 #include <set>
 #include <limits>
 #include <cmath>
+#include <mutex>
 #include <boost/filesystem.hpp>
 #include <boost/filesystem/operations.hpp>
 #include <boost/thread/mutex.hpp>
@@ -1420,14 +1421,14 @@ namespace TwkMovie
         {
             if (!videoToolboxInit(avCodec, avCodecContext, hardwareContext))
             {
-                static bool hasDisplayedError = false;
-                if (!hasDisplayedError)
-                {
-                    std::cout << "WARNING: Hardware decoder is not available "
-                                 "or failed to intialize."
-                              << std::endl;
-                    hasDisplayedError = true;
-                }
+                static std::once_flag warnOnce;
+                std::call_once(warnOnce,
+                               []()
+                               {
+                                   std::cout << "WARNING: Hardware decoder is not available "
+                                                "or failed to intialize."
+                                             << std::endl;
+                               });
             }
         }
 #endif
@@ -3785,14 +3786,15 @@ namespace TwkMovie
         const AVPixFmtDescriptor* desc = av_pix_fmt_desc_get(nativeFormat);
         if (!desc && nativeFormat == AV_PIX_FMT_NONE)
         {
-            static bool warned = false;
-            if (!warned)
-            {
-                std::cout << "WARNING: FFmpeg detected pixel format "
-                             "AV_PIX_FMT_NONE for frames in "
-                          << m_filename << ". Using fallback pixel format: " << av_get_pix_fmt_name(m_pxlFormatOnOpen) << std::endl;
-                warned = true;
-            }
+            static std::once_flag warnOnce;
+            std::call_once(warnOnce,
+                           [this]()
+                           {
+                               std::cout << "WARNING: FFmpeg detected pixel format "
+                                            "AV_PIX_FMT_NONE for frames in "
+                                         << m_filename << ". Using fallback pixel format: " << av_get_pix_fmt_name(m_pxlFormatOnOpen)
+                                         << std::endl;
+                           });
             // Use the pixel format detected when the file was opened as a
             // fallback. Assumes that m_pxlFormatOnOpen is set because the file
             // was opened.