Index: cmake/OpenCVCompilerOptions.cmake
--- cmake/OpenCVCompilerOptions.cmake.orig	2017-12-15 23:30:43.000000000 +0100
+++ cmake/OpenCVCompilerOptions.cmake	2017-12-16 19:20:54.395389000 +0100
@@ -100,24 +100,6 @@
 
 if(CMAKE_COMPILER_IS_GNUCXX)
   # High level of warnings.
-  add_extra_compiler_option(-W)
-  add_extra_compiler_option(-Wall)
-  add_extra_compiler_option(-Werror=return-type)
-  add_extra_compiler_option(-Werror=non-virtual-dtor)
-  add_extra_compiler_option(-Werror=address)
-  add_extra_compiler_option(-Werror=sequence-point)
-  add_extra_compiler_option(-Wformat)
-  add_extra_compiler_option(-Werror=format-security -Wformat)
-  add_extra_compiler_option(-Wmissing-declarations)
-  add_extra_compiler_option(-Wmissing-prototypes)
-  add_extra_compiler_option(-Wstrict-prototypes)
-  add_extra_compiler_option(-Wundef)
-  add_extra_compiler_option(-Winit-self)
-  add_extra_compiler_option(-Wpointer-arith)
-  add_extra_compiler_option(-Wshadow)
-  add_extra_compiler_option(-Wsign-promo)
-  add_extra_compiler_option(-Wuninitialized)
-  add_extra_compiler_option(-Winit-self)
 
   if(ENABLE_NOISY_WARNINGS)
     add_extra_compiler_option(-Wcast-align)
@@ -125,7 +107,6 @@
   else()
     add_extra_compiler_option(-Wno-narrowing)
     add_extra_compiler_option(-Wno-delete-non-virtual-dtor)
-    add_extra_compiler_option(-Wno-unnamed-type-template-args)
     add_extra_compiler_option(-Wno-comment)
     add_extra_compiler_option(-Wno-implicit-fallthrough)
     if(CMAKE_COMPILER_IS_GNUCXX AND CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL 7.2.0)
Index: modules/core/src/utils/filesystem.cpp
--- modules/core/src/utils/filesystem.cpp.orig	2017-12-15 23:30:43.000000000 +0100
+++ modules/core/src/utils/filesystem.cpp	2017-12-16 19:54:15.168153000 +0100
@@ -33,7 +33,7 @@
 #include <errno.h>
 #include <io.h>
 #include <stdio.h>
-#elif defined __linux__ || defined __APPLE__
+#elif defined __linux__ || defined __APPLE__ || defined __FreeBSD__
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -156,7 +156,7 @@
     sz = GetCurrentDirectoryA((DWORD)buf.size(), (char*)buf);
     return cv::String((char*)buf, (size_t)sz);
 #endif
-#elif defined __linux__ || defined __APPLE__
+#elif defined __linux__ || defined __APPLE__ || defined __FreeBSD__
     for(;;)
     {
         char* p = ::getcwd((char*)buf, buf.size());
@@ -190,7 +190,7 @@
 #else
     int result = _mkdir(path.c_str());
 #endif
-#elif defined __linux__ || defined __APPLE__
+#elif defined __linux__ || defined __APPLE__ || defined __FreeBSD__
     int result = mkdir(path.c_str(), 0777);
 #else
     int result = -1;
@@ -305,7 +305,7 @@
     Impl& operator=(const Impl&); // disabled
 };
 
-#elif defined __linux__ || defined __APPLE__
+#elif defined __linux__ || defined __APPLE__ || defined __FreeBSD__
 
 struct FileLock::Impl
 {
Index: modules/dnn/src/torch/THGeneral.cpp
--- modules/dnn/src/torch/THGeneral.cpp.orig	2017-12-15 23:30:43.000000000 +0100
+++ modules/dnn/src/torch/THGeneral.cpp	2017-12-16 19:20:54.395537000 +0100
@@ -3,7 +3,7 @@
 
 #if defined(TH_DISABLE_HEAP_TRACKING)
 #elif (defined(__unix) || defined(_WIN32))
-#include <malloc.h>
+#include <stdlib.h>
 #elif defined(__APPLE__)
 #include <malloc/malloc.h>
 #endif