diff --git a/modules/core/include/opencv2/core/base.hpp b/modules/core/include/opencv2/core/base.hpp
index 61144e999c..5545030b91 100644
--- a/modules/core/include/opencv2/core/base.hpp
+++ b/modules/core/include/opencv2/core/base.hpp
@@ -727,11 +727,7 @@ namespace cudev
 
 namespace ipp
 {
-#if OPENCV_ABI_COMPATIBILITY > 300
 CV_EXPORTS   unsigned long long getIppFeatures();
-#else
-CV_EXPORTS   int getIppFeatures();
-#endif
 CV_EXPORTS   void setIppStatus(int status, const char * const funcname = NULL, const char * const filename = NULL,
                              int line = 0);
 CV_EXPORTS   int getIppStatus();
diff --git a/modules/core/include/opencv2/core/cvdef.h b/modules/core/include/opencv2/core/cvdef.h
index a87ced09d7..64b4dabf97 100644
--- a/modules/core/include/opencv2/core/cvdef.h
+++ b/modules/core/include/opencv2/core/cvdef.h
@@ -251,7 +251,7 @@ typedef union Cv64suf
 }
 Cv64suf;
 
-#define OPENCV_ABI_COMPATIBILITY 300
+#define OPENCV_ABI_COMPATIBILITY 400
 
 #ifdef __OPENCV_BUILD
 #  define DISABLE_OPENCV_24_COMPATIBILITY
diff --git a/modules/core/include/opencv2/core/types.hpp b/modules/core/include/opencv2/core/types.hpp
index 6d8782058a..fdb52efe8e 100644
--- a/modules/core/include/opencv2/core/types.hpp
+++ b/modules/core/include/opencv2/core/types.hpp
@@ -250,11 +250,7 @@ public:
     //! conversion to another data type
     template<typename _Tp2> operator Point3_<_Tp2>() const;
     //! conversion to cv::Vec<>
-#if OPENCV_ABI_COMPATIBILITY > 300
-    template<typename _Tp2> operator Vec<_Tp2, 3>() const;
-#else
     operator Vec<_Tp, 3>() const;
-#endif
 
     //! dot product
     _Tp dot(const Point3_& pt) const;
@@ -1405,19 +1401,11 @@ Point3_<_Tp>::operator Point3_<_Tp2>() const
     return Point3_<_Tp2>(saturate_cast<_Tp2>(x), saturate_cast<_Tp2>(y), saturate_cast<_Tp2>(z));
 }
 
-#if OPENCV_ABI_COMPATIBILITY > 300
-template<typename _Tp> template<typename _Tp2> inline
-Point3_<_Tp>::operator Vec<_Tp2, 3>() const
-{
-    return Vec<_Tp2, 3>(x, y, z);
-}
-#else
 template<typename _Tp> inline
 Point3_<_Tp>::operator Vec<_Tp, 3>() const
 {
     return Vec<_Tp, 3>(x, y, z);
 }
-#endif
 
 template<typename _Tp> inline
 Point3_<_Tp>& Point3_<_Tp>::operator = (const Point3_& pt)
diff --git a/modules/core/include/opencv2/core/utility.hpp b/modules/core/include/opencv2/core/utility.hpp
index 8ee82b82cf..f72f13a5bb 100644
--- a/modules/core/include/opencv2/core/utility.hpp
+++ b/modules/core/include/opencv2/core/utility.hpp
@@ -689,17 +689,10 @@ protected:
     virtual ~TLSDataContainer();
 
     void  gatherData(std::vector<void*> &data) const;
-#if OPENCV_ABI_COMPATIBILITY > 300
     void* getData() const;
     void  release();
 
 private:
-#else
-    void  release();
-
-public:
-    void* getData() const;
-#endif
     virtual void* createDataInstance() const = 0;
     virtual void  deleteDataInstance(void* pData) const = 0;
 
diff --git a/modules/core/src/system.cpp b/modules/core/src/system.cpp
index b53f7c9c43..0f20248a3b 100644
--- a/modules/core/src/system.cpp
+++ b/modules/core/src/system.cpp
@@ -2023,18 +2023,10 @@ static IPPInitSingleton& getIPPSingleton()
 }
 #endif
 
-#if OPENCV_ABI_COMPATIBILITY > 300
 unsigned long long getIppFeatures()
-#else
-int getIppFeatures()
-#endif
 {
 #ifdef HAVE_IPP
-#if OPENCV_ABI_COMPATIBILITY > 300
     return getIPPSingleton().ippFeatures;
-#else
-    return (int)getIPPSingleton().ippFeatures;
-#endif
 #else
     return 0;
 #endif