This problem occurs in thegit/master as well as the current development or stable releases. I'm running on a slackware box using gcc 6.2.0. Here's what make shows: [ 0%] Building CXX object Source/WTF/wtf/CMakeFiles/WTF.dir/Assertions.cpp.o In file included from /home/ronis/Project/notar/GNOME/garnome/svn/webkitgtk/work/main.d/WebKit-git/Source/WTF/wtf/Assertions.cpp:41:0: /home/ronis/Project/notar/GNOME/garnome/svn/webkitgtk/work/main.d/WebKit-git/Source/WTF/wtf/Lock.h:156:5: error: ‘WTF_MAKE_FAST_ALLOCATED’ does not name a type WTF_MAKE_FAST_ALLOCATED; ^~~~~~~~~~~~~~~~~~~~~~~ make[3]: *** [Source/WTF/wtf/CMakeFiles/WTF.dir/Assertions.cpp.o] Error 1 Here's what I'm using for my CMAKE_FLAGS: CMAKE_FLAGS = -DCMAKE_INSTALL_PREFIX=$(main_prefix) \ -DCMAKE_C_FLAGS="$(CFLAGS) -I$(prefix)/include/NetworkManager -DENABLE_WEBKIT=ON -I$(prefix)/include -I$(prefix)/include/glib-2.0" \ -DCMAKE_CXX_FLAGS="$(CXXFLAGS) -fpermissive -I$(prefix)/include/NetworkManager -DENABLE_WEBKIT=ON -I$(prefix)/include/glib-2.0 -fpermissive" "-DENABLE_INTROSPECTION=OFF"\ -DPORT="GTK" -Wno-dev "-DCMAKE_BUILD_TYPE=Release" "-DENABLE_WEBKIT=ON"