diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9b026a88..fd6f1e2b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -27,7 +27,7 @@ linux-builder:
   except:
   - tags
   tags:
-    - linux
+    - linux-bionic
 
 mac-builder:
   stage: build-libopenshot
@@ -43,7 +43,7 @@ mac-builder:
     - unzip artifacts.zip
     - export LIBOPENSHOT_AUDIO_DIR=$CI_PROJECT_DIR/build/install-x64
     - mkdir -p build; cd build;
-    - cmake -DCMAKE_CXX_FLAGS=-I\ /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -D"CMAKE_INSTALL_PREFIX:PATH=$CI_PROJECT_DIR/build/install-x64" -DCMAKE_CXX_COMPILER=/usr/local/opt/gcc@8/bin/g++-8 -DCMAKE_C_COMPILER=/usr/local/opt/gcc@8/bin/gcc-8 -DCMAKE_PREFIX_PATH=/usr/local/qt5/5.5/clang_64 -DPYTHON_INCLUDE_DIR=/Library/Frameworks/Python.framework/Versions/3.6/include/python3.6m -DPYTHON_LIBRARY=/Library/Frameworks/Python.framework/Versions/3.6/lib/libpython3.6.dylib -DPYTHON_MODULE_PATH=python -DPython_FRAMEWORKS=/Library/Frameworks/Python.framework/ -D"CMAKE_BUILD_TYPE:STRING=Release" -D"CMAKE_OSX_SYSROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk" -D"CMAKE_OSX_DEPLOYMENT_TARGET=10.9" -D"CMAKE_INSTALL_RPATH_USE_LINK_PATH=1" -D"ENABLE_RUBY=0" ../
+    - cmake -DCMAKE_EXE_LINKER_FLAGS="-stdlib=libc++" -DCMAKE_SHARED_LINKER_FLAGS="-stdlib=libc++" -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -D"CMAKE_INSTALL_PREFIX:PATH=$CI_PROJECT_DIR/build/install-x64" -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang -DCMAKE_PREFIX_PATH=/usr/local/qt5.15.X/qt5.15/5.15.0/clang_64/ -DPYTHON_INCLUDE_DIR=/Library/Frameworks/Python.framework/Versions/3.6/include/python3.6m -DPYTHON_LIBRARY=/Library/Frameworks/Python.framework/Versions/3.6/lib/libpython3.6.dylib -DPYTHON_MODULE_PATH=python -DPython_FRAMEWORKS=/Library/Frameworks/Python.framework/ -D"CMAKE_BUILD_TYPE:STRING=Release" -D"CMAKE_OSX_SYSROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk" -D"CMAKE_OSX_DEPLOYMENT_TARGET=10.9" -D"CMAKE_INSTALL_RPATH_USE_LINK_PATH=1" -D"ENABLE_RUBY=0" ../
     - make
     - make install
     - echo -e "CI_PROJECT_NAME:$CI_PROJECT_NAME\nCI_COMMIT_REF_NAME:$CI_COMMIT_REF_NAME\nCI_COMMIT_SHA:$CI_COMMIT_SHA\nCI_JOB_ID:$CI_JOB_ID" > "install-x64/share/$CI_PROJECT_NAME"
diff --git a/include/ChunkReader.h b/include/ChunkReader.h
index cd7cd67f..50b26083 100644
--- a/include/ChunkReader.h
+++ b/include/ChunkReader.h
@@ -37,10 +37,10 @@
 #include <iostream>
 #include <fstream>
 #include <omp.h>
-#include <QtCore/qdir.h>
-#include <stdio.h>
+#include <cstdio>
 #include <cstdlib>
 #include <memory>
+#include <QtCore/QDir>
 #include "Json.h"
 #include "CacheMemory.h"
 #include "Exceptions.h"
diff --git a/include/ChunkWriter.h b/include/ChunkWriter.h
index 5fee5a37..a63e4ca1 100644
--- a/include/ChunkWriter.h
+++ b/include/ChunkWriter.h
@@ -34,19 +34,19 @@
 #include "ReaderBase.h"
 #include "WriterBase.h"
 #include "FFmpegWriter.h"
+#include "CacheMemory.h"
+#include "Exceptions.h"
+#include "Json.h"
 
 #include <cmath>
 #include <ctime>
 #include <iostream>
 #include <fstream>
-#include <omp.h>
-#include <QtCore/qdir.h>
-#include <stdio.h>
+#include <cstdio>
 #include <sstream>
 #include <unistd.h>
-#include "CacheMemory.h"
-#include "Exceptions.h"
-#include "Json.h"
+#include <omp.h>
+#include <QtCore/QDir>
 
 
 namespace openshot
diff --git a/include/Fraction.h b/include/Fraction.h
index 9ffcda1f..88c16fbc 100644
--- a/include/Fraction.h
+++ b/include/Fraction.h
@@ -31,7 +31,7 @@
 #ifndef OPENSHOT_FRACTION_H
 #define OPENSHOT_FRACTION_H
 
-#include <math.h>
+#include <cmath>
 
 namespace openshot {
 
diff --git a/include/FrameMapper.h b/include/FrameMapper.h
index 35dc8fb7..e78401a9 100644
--- a/include/FrameMapper.h
+++ b/include/FrameMapper.h
@@ -33,7 +33,7 @@
 
 #include <assert.h>
 #include <iostream>
-#include <math.h>
+#include <cmath>
 #include <vector>
 #include <memory>
 #include "CacheMemory.h"
diff --git a/include/KeyFrame.h b/include/KeyFrame.h
index ee58da8f..6424473a 100644
--- a/include/KeyFrame.h
+++ b/include/KeyFrame.h
@@ -33,7 +33,7 @@
 
 #include <iostream>
 #include <iomanip>
-#include <math.h>
+#include <cmath>
 #include <assert.h>
 #include <vector>
 #include "Exceptions.h"
diff --git a/include/OpenMPUtilities.h b/include/OpenMPUtilities.h
index 9810d636..30bdd199 100644
--- a/include/OpenMPUtilities.h
+++ b/include/OpenMPUtilities.h
@@ -32,8 +32,8 @@
 #define OPENSHOT_OPENMP_UTILITIES_H
 
 #include <omp.h>
-#include <stdlib.h>
-#include <string.h>
+#include <algorithm>
+#include <string>
 
 #include "Settings.h"
 
diff --git a/include/Profiles.h b/include/Profiles.h
index 3b5ebd0d..1de7c072 100644
--- a/include/Profiles.h
+++ b/include/Profiles.h
@@ -35,12 +35,12 @@
 #include <string>
 #include <sstream>
 #include <fstream>
-#include <QtCore/qstring.h>
-#include <QtCore/qstringlist.h>
-#include <QtCore/qfile.h>
+#include <QtCore/QString>
+#include <QtCore/QStringList>
+#include <QtCore/QFile>
 #include <QTextStream>
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 #include "Exceptions.h"
 #include "Fraction.h"
 #include "Json.h"
diff --git a/include/Qt/PlayerDemo.h b/include/Qt/PlayerDemo.h
index f444334b..8dca83fc 100644
--- a/include/Qt/PlayerDemo.h
+++ b/include/Qt/PlayerDemo.h
@@ -31,12 +31,12 @@
 #ifndef OPENSHOT_PLAYER_DEMO_H
 #define OPENSHOT_PLAYER_DEMO_H
 
-#include <QtWidgets/QWidget>
-#include <QtWidgets/QBoxLayout>
-#include <QtWidgets/QMenuBar>
-#include <QtWidgets/QMenu>
-#include <QtGui/qevent.h>
-#include <QApplication>
+#include <QObject>
+#include <QWidget>
+#include <QKeyEvent>
+#include <QCloseEvent>
+#include <QVBoxLayout>
+#include <QMenuBar>
 
 #include "VideoRenderWidget.h"
 
diff --git a/include/ReaderBase.h b/include/ReaderBase.h
index dfb9873d..ab765753 100644
--- a/include/ReaderBase.h
+++ b/include/ReaderBase.h
@@ -43,7 +43,7 @@
 #include "Frame.h"
 #include "Json.h"
 #include "ZmqLogger.h"
-#include <QtCore/qstring.h>
+#include <QString>
 #include <QGraphicsItem>
 #include <QGraphicsScene>
 #include <QGraphicsPixmapItem>
diff --git a/include/RendererBase.h b/include/RendererBase.h
index 1c526937..5e65ea87 100644
--- a/include/RendererBase.h
+++ b/include/RendererBase.h
@@ -32,7 +32,7 @@
 #define OPENSHOT_RENDERER_BASE_H
 
 #include "Frame.h"
-#include <stdlib.h> // for realloc
+#include <cstdlib> // for realloc
 #include <memory>
 
 namespace openshot
diff --git a/include/Settings.h b/include/Settings.h
index e82bf56b..4b12c612 100644
--- a/include/Settings.h
+++ b/include/Settings.h
@@ -35,11 +35,11 @@
 #include <iostream>
 #include <iomanip>
 #include <fstream>
-#include <stdlib.h>
+#include <cstdlib>
 #include <string>
 #include <sstream>
-#include <stdio.h>
-#include <time.h>
+#include <cstdio>
+#include <ctime>
 #include <zmq.hpp>
 #include <unistd.h>
 #include "JuceHeader.h"
diff --git a/include/ZmqLogger.h b/include/ZmqLogger.h
index c165299e..af1eea6f 100644
--- a/include/ZmqLogger.h
+++ b/include/ZmqLogger.h
@@ -35,11 +35,11 @@
 #include <iostream>
 #include <iomanip>
 #include <fstream>
-#include <stdlib.h>
+#include <cstdlib>
 #include <string>
 #include <sstream>
-#include <stdio.h>
-#include <time.h>
+#include <cstdio>
+#include <ctime>
 #include <zmq.hpp>
 #include <unistd.h>
 #include "JuceHeader.h"
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ad5b5806..dec7c853 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -34,6 +34,16 @@ if (POLICY CMP0057)
   cmake_policy(SET CMP0057 NEW)
 endif()
 
+# Juce requires either DEBUG or NDEBUG to be defined on MacOS.
+# -DNDEBUG is set by cmake for all release configs, so add
+# -DDEBUG for debug builds. We'll do this for all OSes, even
+# though only MacOS requires it.
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DDEBUG")
+# Make sure we've picked some build type, default to debug
+if(NOT DEFINED CMAKE_BUILD_TYPE OR CMAKE_BUILD_TYPE STREQUAL "")
+    set(CMAKE_BUILD_TYPE "Debug")
+endif()
+
 ################ WINDOWS ##################
 # Set some compiler options for Windows
 # required for libopenshot-audio headers
@@ -45,7 +55,6 @@ endif()
 if (APPLE)
 	# If you still get errors compiling with GCC 4.8, mac headers need to be patched: http://hamelot.co.uk/programming/osx-gcc-dispatch_block_t-has-not-been-declared-invalid-typedef/
 	set_property(GLOBAL PROPERTY JUCE_MAC "JUCE_MAC")
-	add_definitions(-DNDEBUG)
 	set(EXTENSION "mm")
 	set(JUCE_PLATFORM_SPECIFIC_DIR build/macosx/platform_specific_code)
 	set(JUCE_PLATFORM_SPECIFIC_LIBRARIES "-framework Carbon -framework Cocoa -framework CoreFoundation -framework CoreAudio -framework CoreMidi -framework IOKit -framework AGL -framework AudioToolbox -framework QuartzCore -lobjc -framework Accelerate")
diff --git a/src/Frame.cpp b/src/Frame.cpp
index 764b9651..cf47556a 100644
--- a/src/Frame.cpp
+++ b/src/Frame.cpp
@@ -992,7 +992,7 @@ void Frame::Play()
 
 	// Output error (if any)
 	if (error.isNotEmpty()) {
-		cout << "Error on initialise(): " << error.toStdString() << endl;
+		cout << "Error on initialise(): " << error << endl;
 	}
 
 	juce::AudioSourcePlayer audioSourcePlayer;
diff --git a/src/Qt/PlayerDemo.cpp b/src/Qt/PlayerDemo.cpp
index ba20e5cf..e5f0e11d 100644
--- a/src/Qt/PlayerDemo.cpp
+++ b/src/Qt/PlayerDemo.cpp
@@ -28,11 +28,18 @@
  * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "stdio.h"
+#include <cstdio>
 #include "../../include/QtPlayer.h"
 #include "../../include/Qt/PlayerDemo.h"
 #include <QMessageBox>
 #include <QFileDialog>
+#include <QWidget>
+#include <QBoxLayout>
+#include <QMenuBar>
+#include <QMenu>
+#include <QKeyEvent>
+#include <QCloseEvent>
+#include <QApplication>
 
 PlayerDemo::PlayerDemo(QWidget *parent)
     : QWidget(parent)
diff --git a/src/examples/ExampleHtml.cpp b/src/examples/ExampleHtml.cpp
index f315e252..576961bc 100644
--- a/src/examples/ExampleHtml.cpp
+++ b/src/examples/ExampleHtml.cpp
@@ -32,11 +32,12 @@
 #include <fstream>
 #include <iostream>
 #include <memory>
-#include "../../include/OpenShot.h"
-//#include "../../include/CrashHandler.h"
 #include <QGuiApplication>
 #include <QTimer>
 
+#include "../../include/OpenShot.h"
+#include "../../include/CrashHandler.h"
+
 using namespace openshot;
 
 int main(int argc, char* argv[]) {