diff --git a/3rdparty/libtiff/CMakeLists.txt b/3rdparty/libtiff/CMakeLists.txt
index 924c22e8a..ce2904ad4 100644
--- a/3rdparty/libtiff/CMakeLists.txt
+++ b/3rdparty/libtiff/CMakeLists.txt
@@ -88,6 +88,10 @@ endif()
 
 add_library(${the_target} STATIC ${lib_srcs} ${lib_hdrs})
 
+if(CMAKE_COMPILER_IS_GNUCXX)
+  set_source_files_properties(tif_stream.cxx PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+endif()
+
 set_target_properties(${the_target}
 	PROPERTIES
 	OUTPUT_NAME "${the_target}"
diff --git a/modules/core/include/opencv2/core/operations.hpp b/modules/core/include/opencv2/core/operations.hpp
index 5f1d1c2a8..a79b99bb8 100644
--- a/modules/core/include/opencv2/core/operations.hpp
+++ b/modules/core/include/opencv2/core/operations.hpp
@@ -3655,12 +3655,13 @@ public:
     static int isInstance(const void* ptr)
     {
         static _ClsName dummy;
+        static void* dummyp = &dummy;
         union
         {
             const void* p;
             const void** pp;
         } a, b;
-        a.p = &dummy;
+        a.p = dummyp;
         b.p = ptr;
         return *a.pp == *b.pp;
     }
diff --git a/modules/objdetect/src/lsvmtbbversion.cpp b/modules/objdetect/src/lsvmtbbversion.cpp
index 3c87930d3..c9f174a97 100644
--- a/modules/objdetect/src/lsvmtbbversion.cpp
+++ b/modules/objdetect/src/lsvmtbbversion.cpp
@@ -32,8 +32,8 @@ public:
                      CvPoint ****_partsDisplacement) :
     n(_n), b(_b), maxXBorder(_maxXBorder), 
         maxYBorder(_maxYBorder), scoreThreshold(_scoreThreshold),
-        kLevels(_kLevels), score(_score), points(_points), kPoints(_kPoints),
-        partsDisplacement(_partsDisplacement)
+        kLevels(_kLevels), score(_score), points(_points),
+        partsDisplacement(_partsDisplacement), kPoints(_kPoints)
     {
         filters = _filters;
         H = _H;