--- webkitgtk-2.42.4.old/Source/cmake/OptionsGTK.cmake
+++ webkitgtk-2.42.4/Source/cmake/OptionsGTK.cmake
@@ -13,6 +13,8 @@
 
 set(USER_AGENT_BRANDING "" CACHE STRING "Branding to add to user agent string")
 
+set(THREADS_PREFER_PTHREAD_FLAG ON)
+
 find_package(Cairo 1.16.0 REQUIRED)
 find_package(Fontconfig 2.13.0 REQUIRED)
 find_package(Freetype 2.9.0 REQUIRED)
--- webkitgtk-2.42.4.old/Source/cmake/OptionsJSCOnly.cmake
+++ webkitgtk-2.42.4/Source/cmake/OptionsJSCOnly.cmake
@@ -1,3 +1,4 @@
+set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)
 
 if (MSVC)