Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -207,12 +207,14 @@
 				[Whether we have libkern/OSAtomic.h])])
 	fi
 
 	AC_MSG_CHECKING(for atomic operations)
 	if test x"$have_gcc_atomic_ops" = x"yes"; then
+		AC_DEFINE(OF_ATOMIC_OPS, 1, [Whether we have atomic operations])
 		AC_MSG_RESULT(gcc builtins)
 	elif test x"$have_libkern_osatomic_h" = x"yes"; then
+		AC_DEFINE(OF_ATOMIC_OPS, 1, [Whether we have atomic operations])
 		AC_MSG_RESULT(libkern/OSAtomic.h)
 	else
 		AC_MSG_RESULT(none)
 		AC_MSG_ERROR(No atomic operations found! Try --disable-threads.)
 	fi

Index: src/objfw-defs.h.in
==================================================================
--- src/objfw-defs.h.in
+++ src/objfw-defs.h.in
@@ -1,10 +1,11 @@
 #undef OF_APPLE_RUNTIME
+#undef OF_ATOMIC_OPS
 #undef OF_BIG_ENDIAN
 #undef OF_GNU_RUNTIME
 #undef OF_HAVE_ASPRINTF
 #undef OF_HAVE_GCC_ATOMIC_OPS
 #undef OF_HAVE_LIBKERN_OSATOMIC_H
 #undef OF_HAVE_PTHREADS
 #undef OF_PLUGINS
 #undef OF_THREADS
 #undef SIZE_MAX