diff --git a/CC/src/NormalizedProgress.cpp b/CC/src/NormalizedProgress.cpp
index 5caa6402c1..4ff3fe63e5 100644
--- a/CC/src/NormalizedProgress.cpp
+++ b/CC/src/NormalizedProgress.cpp
@@ -26,16 +26,8 @@
 //we use Qt for the atomic counter
 #include <QAtomicInt>
 
-//! Qt 4/5 compatible QAtomicInt
 class AtomicCounter : public QAtomicInt
 {
-public:
-	AtomicCounter() : QAtomicInt(0) {}
-
-#if (QT_VERSION < QT_VERSION_CHECK(5, 0, 0))
-	inline int load() { return *this; }
-	inline void store(int value) { *static_cast<QAtomicInt*>(this) = value; }
-#endif
 };
 
 #else
diff --git a/common/ccApplicationBase.cpp b/common/ccApplicationBase.cpp
index 7085e5db49..0883d7223e 100644
--- a/common/ccApplicationBase.cpp
+++ b/common/ccApplicationBase.cpp
@@ -38,6 +38,11 @@
 #include "ccTranslationManager.h"
 
 
+#if (QT_VERSION < QT_VERSION_CHECK(5, 5, 0))
+#error CloudCompare does not support versions of Qt prior to 5.5
+#endif
+
+
 void ccApplicationBase::init(bool noOpenGLSupport)
 {
 	if (!noOpenGLSupport)
diff --git a/libs/qCC_db/ccIncludeGL.h b/libs/qCC_db/ccIncludeGL.h
index aad62600a6..a725095e92 100644
--- a/libs/qCC_db/ccIncludeGL.h
+++ b/libs/qCC_db/ccIncludeGL.h
@@ -26,11 +26,6 @@
 //Qt
 #include <QOpenGLFunctions_2_1>
 
-//temporary test for QOpenGLWidget integration
-#if (QT_VERSION < QT_VERSION_CHECK(5, 4, 0))
-#error	Error: CloudCompare does not support versions of Qt prior to 5.4 anymore!
-#endif
-
 //! Shortcuts to OpenGL commands independent on the input type
 class ccGL
 {
diff --git a/libs/qCC_io/E57Filter.cpp b/libs/qCC_io/E57Filter.cpp
index 8adacee3d7..64a773cf3b 100644
--- a/libs/qCC_io/E57Filter.cpp
+++ b/libs/qCC_io/E57Filter.cpp
@@ -2050,7 +2050,9 @@ static ccHObject* LoadImage(const e57::Node& node, QString& associatedData3DGuid
 	case E57_CYLINDRICAL:
 	case E57_SPHERICAL:
 		ccLog::Warning("[E57] Unhandled camera type (image will be loaded as is)");
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 8, 0))
 		Q_FALLTHROUGH();
+#endif
 	case E57_VISUAL:
 		imageObj = new ccImage();
 		break;
diff --git a/plugins/ccDefaultPluginInterface.cpp b/plugins/ccDefaultPluginInterface.cpp
index 1a774c49b3..4ce89b7bc1 100644
--- a/plugins/ccDefaultPluginInterface.cpp
+++ b/plugins/ccDefaultPluginInterface.cpp
@@ -21,6 +21,7 @@
 #include <QJsonObject>
 
 #include "ccDefaultPluginInterface.h"
+#include "ccLog.h"
 
 
 // This class keeps JSON from being included in the header
diff --git a/plugins/ccPluginInterface.h b/plugins/ccPluginInterface.h
index 3ced3384a6..cddcfd51d1 100644
--- a/plugins/ccPluginInterface.h
+++ b/plugins/ccPluginInterface.h
@@ -18,9 +18,6 @@
 #ifndef CC_PLUGIN_INTERFACE_HEADER
 #define CC_PLUGIN_INTERFACE_HEADER
 
-//qCC_db
-#include <ccObject.h> //for CC_QT5 def
-
 //Qt
 #include <QIcon>
 #include <QList>
@@ -30,11 +27,6 @@
 
 //Qt version
 #include <qglobal.h>
-#ifndef CC_QT5
-	#if (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
-		#define CC_QT5
-	#endif
-#endif
 
 class ccExternalFactory;
 class ccCommandLineInterface;
diff --git a/plugins/core/qCSF/qCSF.cpp b/plugins/core/qCSF/qCSF.cpp
index 1faa9d4f92..1007b63247 100644
--- a/plugins/core/qCSF/qCSF.cpp
+++ b/plugins/core/qCSF/qCSF.cpp
@@ -58,11 +58,6 @@
 //CSF
 #include <CSF.h>
 
-#ifndef CC_QT5
-//Don't forget to replace 'qMyPlugin' by your own plugin class name here also!
-Q_EXPORT_PLUGIN2(qCSF,qCSF);
-#endif
-
 qCSF::qCSF(QObject* parent)
 	: QObject( parent )
 	, ccStdPluginInterface( ":/CC/plugin/qCSF/info.json" )
diff --git a/qCC/ccConsole.cpp b/qCC/ccConsole.cpp
index 616a00d57e..5b3d88fb7a 100644
--- a/qCC/ccConsole.cpp
+++ b/qCC/ccConsole.cpp
@@ -118,12 +118,10 @@ void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const QS
 		message.prepend("[Qt FATAL] ");
 		ccLog::Warning(message);
 		break;
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 5, 0)) //DGM: QtInfoMsg is only defined since version 5.5
 	case QtInfoMsg:
 		message.prepend("[Qt INFO] ");
 		ccLog::Warning(message);
 		break;
-#endif
 	}
 	
 #ifdef QT_DEBUG
@@ -133,9 +131,7 @@ void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const QS
 	{
 		case QtDebugMsg:
 		case QtWarningMsg:
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 5, 0))
 		case QtInfoMsg:
-#endif
 			std::cout << message.toStdString() << std::endl;
 			break;