diff --git a/CMakeLists.txt b/CMakeLists.txt
index aee1a9263..96fcc7a1a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,7 +24,12 @@ set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
 if(CMAKE_COMPILER_IS_GNUCXX)
   if(CMAKE_SYSTEM_NAME MATCHES Linux)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wnon-virtual-dtor -Wno-long-long -ansi -Wundef -Wcast-align -Wchar-subscripts -Wall -W -Wpointer-arith -Wwrite-strings -Wformat-security -Wextra -fno-exceptions -fno-check-new -fno-common -fstrict-aliasing")
+    include(CheckCXXCompilerFlag)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wnon-virtual-dtor -Wno-long-long -ansi -Wundef -Wcast-align -Wchar-subscripts -Wall -W -Wpointer-arith -Wwrite-strings -Wformat-security -fno-exceptions -fno-check-new -fno-common -fstrict-aliasing")
+    check_cxx_compiler_flag("-Wextra" has_wextra)
+    if(has_wextra)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wextra")
+    endif()
     if(NOT EIGEN_TEST_LIB)
       set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic")
     endif(NOT EIGEN_TEST_LIB)
diff --git a/Eigen/StdVector b/Eigen/StdVector
index c0744d6a0..5a88402a5 100644
--- a/Eigen/StdVector
+++ b/Eigen/StdVector
@@ -144,4 +144,4 @@ class vector<T,DummyAlloc,true>
 
 #endif // EIGEN_STDVECTOR_MODULE_H
 
-#endif // EIGEN_USE_NEW_STDVECTOR
\ No newline at end of file
+#endif // EIGEN_USE_NEW_STDVECTOR
diff --git a/Eigen/src/Core/MapBase.h b/Eigen/src/Core/MapBase.h
index c923bc340..e79748e7d 100644
--- a/Eigen/src/Core/MapBase.h
+++ b/Eigen/src/Core/MapBase.h
@@ -66,11 +66,11 @@ template<typename Derived> class MapBase
     inline const Scalar* data() const { return m_data; }
 
     template<bool IsForceAligned,typename Dummy> struct force_aligned_impl {
-      AlignedDerivedType static run(MapBase& a) { return a.derived(); }
+      static AlignedDerivedType run(MapBase& a) { return a.derived(); }
     };
 
     template<typename Dummy> struct force_aligned_impl<false,Dummy> {
-      AlignedDerivedType static run(MapBase& a) { return a.derived()._convertToForceAligned(); }
+      static AlignedDerivedType run(MapBase& a) { return a.derived()._convertToForceAligned(); }
     };
 
     /** \returns an expression equivalent to \c *this but having the \c PacketAccess constant
diff --git a/Eigen/src/Core/util/XprHelper.h b/Eigen/src/Core/util/XprHelper.h
index 12d6f9a3a..7cadd343d 100644
--- a/Eigen/src/Core/util/XprHelper.h
+++ b/Eigen/src/Core/util/XprHelper.h
@@ -37,6 +37,10 @@
 //classes inheriting ei_no_assignment_operator don't generate a default operator=.
 class ei_no_assignment_operator
 {
+#if EIGEN_GCC3_OR_OLDER
+  protected:
+    void nevermind_this_is_just_to_work_around_a_stupid_gcc3_warning();
+#endif
   private:
     ei_no_assignment_operator& operator=(const ei_no_assignment_operator&);
 };