diff --git a/CMakeLists.txt b/CMakeLists.txt
index b0a7f32f..f02cbf51 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -55,6 +55,21 @@ ADD_DEFINITIONS(-DPROJECT_NAME="${PROJECT_NAME}")
 ####### DEPENDENCIES #######
 FIND_PACKAGE(OpenCV REQUIRED) # tested on 2.3.1
 
+IF(OpenCV_VERSION_MAJOR EQUAL 4)
+  IF(NOT MSVC)
+    include(CheckCXXCompilerFlag)
+    CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
+    CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
+    IF(COMPILER_SUPPORTS_CXX11)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+    ELSEIF(COMPILER_SUPPORTS_CXX0X)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
+    ELSE()
+      message(STATUS "The compiler ${CMAKE_CXX_COMPILER} has no C++11 support. Please use a different C++ compiler.")
+    ENDIF()
+  ENDIF(NOT MSVC)
+ENDIF(OpenCV_VERSION_MAJOR EQUAL 4)
+
 # look for Qt5 before Qt4
 FIND_PACKAGE(Qt5 COMPONENTS Widgets Core Gui Network QUIET)
 IF(NOT Qt5_FOUND)
@@ -66,10 +81,19 @@ FIND_PACKAGE(Tcmalloc QUIET)
 
 FIND_PACKAGE(ZLIB REQUIRED QUIET)
 
-SET(NONFREE 0)
-IF(OPENCV_NONFREE_FOUND OR OPENCV_XFEATURES2D_FOUND)
-   SET(NONFREE 1)
-ENDIF(OPENCV_NONFREE_FOUND OR OPENCV_XFEATURES2D_FOUND)
+SET(NONFREE 1)
+IF(NOT (OPENCV_NONFREE_FOUND OR OPENCV_XFEATURES2D_FOUND))
+   SET(NONFREE 0)
+ELSEIF(OpenCV_VERSION VERSION_GREATER "3.4.2")
+  FIND_FILE(OpenCV_MODULES_HPP opencv2/opencv_modules.hpp 
+    PATHS ${OpenCV_INCLUDE_DIRS}
+    NO_DEFAULT_PATH)
+  FILE(READ ${OpenCV_MODULES_HPP} TMPTXT)
+  STRING(FIND "${TMPTXT}" "#define OPENCV_ENABLE_NONFREE" matchres)
+  IF(${matchres} EQUAL -1)
+    SET(NONFREE 0)
+  ENDIF(${matchres} EQUAL -1)
+ENDIF()
 
 CONFIGURE_FILE(Version.h.in ${PROJECT_SOURCE_DIR}/include/${PROJECT_PREFIX}/Version.h)
 
@@ -257,9 +281,9 @@ IF(NOT CATKIN_BUILD)
      ENDIF()
    ELSE()
      IF(OPENCV_XFEATURES2D_FOUND)
-       MESSAGE(STATUS "  With OpenCV 3 xfeatures2d module (SIFT/SURF/BRIEF/FREAK) = YES")
+       MESSAGE(STATUS "  With OpenCV ${OpenCV_VERSION_MAJOR} xfeatures2d module (SIFT/SURF/BRIEF/FREAK) = YES")
      ELSE()
-       MESSAGE(STATUS "  With OpenCV 3 xfeatures2d module (SIFT/SURF/BRIEF/FREAK) = NO (not found)")
+       MESSAGE(STATUS "  With OpenCV ${OpenCV_VERSION_MAJOR} xfeatures2d module (SIFT/SURF/BRIEF/FREAK) = NO (not found)")
      ENDIF()
    ENDIF()
 
diff --git a/src/AddObjectDialog.cpp b/src/AddObjectDialog.cpp
index a4260861..fefbcf7f 100644
--- a/src/AddObjectDialog.cpp
+++ b/src/AddObjectDialog.cpp
@@ -44,6 +44,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <opencv2/imgproc/imgproc.hpp>
 #include <opencv2/highgui/highgui.hpp>
+#include <opencv2/imgproc/imgproc_c.h>
 
 namespace find_object {
 
diff --git a/src/Camera.cpp b/src/Camera.cpp
index 406d4149..6630b6b3 100644
--- a/src/Camera.cpp
+++ b/src/Camera.cpp
@@ -32,6 +32,9 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <stdio.h>
 #include <opencv2/imgproc/imgproc.hpp>
+#if CV_MAJOR_VERSION > 3
+#include <opencv2/videoio/videoio_c.h>
+#endif
 #include <QtCore/QFile>
 #include "utilite/UDirectory.h"
 #include "CameraTcpServer.h"
diff --git a/src/FindObject.cpp b/src/FindObject.cpp
index 187bd6fe..e357c668 100644
--- a/src/FindObject.cpp
+++ b/src/FindObject.cpp
@@ -42,6 +42,10 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <QGraphicsRectItem>
 #include <stdio.h>
 
+#if CV_MAJOR_VERSION > 3
+#include <opencv2/core/types_c.h>
+#endif
+
 namespace find_object {
 
 FindObject::FindObject(bool keepImagesInRAM, QObject * parent) :
diff --git a/src/Settings.cpp b/src/Settings.cpp
index 523bc7ad..f1dcc56e 100644
--- a/src/Settings.cpp
+++ b/src/Settings.cpp
@@ -817,7 +817,11 @@ Feature2D * Settings::createKeypointDetector()
 								getFeature2D_ORB_edgeThreshold(),
 								getFeature2D_ORB_firstLevel(),
 								getFeature2D_ORB_WTA_K(),
+#if CV_MAJOR_VERSION > 3
+								(cv::ORB::ScoreType)getFeature2D_ORB_scoreType(),
+#else
 								getFeature2D_ORB_scoreType(),
+#endif
 								getFeature2D_ORB_patchSize(),
 								getFeature2D_Fast_threshold()));
 #endif
@@ -1061,7 +1065,11 @@ Feature2D * Settings::createDescriptorExtractor()
 								getFeature2D_ORB_edgeThreshold(),
 								getFeature2D_ORB_firstLevel(),
 								getFeature2D_ORB_WTA_K(),
+#if CV_MAJOR_VERSION > 3
+								(cv::ORB::ScoreType)getFeature2D_ORB_scoreType(),
+#else
 								getFeature2D_ORB_scoreType(),
+#endif
 								getFeature2D_ORB_patchSize(),
 								getFeature2D_Fast_threshold()));
 #endif