@@ -104,11 +104,11 @@
 
 AC_DEFINE_UNQUOTED(PLUGIN_SUFFIX, "$PLUGIN_SUFFIX", [Suffix for plugins])
 AS_IF([test x"$PLUGIN_SUFFIX" != x""], [
 	AC_SUBST(USE_SRCS_PLUGINS, '${SRCS_PLUGINS}')
 	AC_SUBST(TESTPLUGIN, "plugin")
-	AC_DEFINE(OF_PLUGINS, 1, [Whether we have plugin support])
+	AC_DEFINE(OF_HAVE_PLUGINS, 1, [Whether we have plugin support])
 ])
 
 objc_runtime="ObjFW runtime"
 AC_CHECK_HEADER(objc/objc.h)
 AC_MSG_CHECKING(which Objective C runtime to use)
@@ -402,14 +402,14 @@
 ])
 test x"$have_asprintf" != x"yes" -a x"$ac_cv_snprintf_useful_ret" != x"yes" && \
 	AC_MSG_ERROR(No asprintf and no snprintf returning required space!)
 
 AC_CHECK_FUNC(arc4random, [
-	AC_DEFINE(OF_HAVE_ARC4RANDOM, 1, [Whether we have arc4random()])
+	AC_DEFINE(HAVE_ARC4RANDOM, 1, [Whether we have arc4random()])
 ], [
 	AC_CHECK_FUNC(random, [
-		AC_DEFINE(OF_HAVE_RANDOM, 1, [Whether we have random()])
+		AC_DEFINE(HAVE_RANDOM, 1, [Whether we have random()])
 	])
 ])
 
 AC_CHECK_LIB(dl, dlopen, LIBS="$LIBS -ldl")
 
@@ -452,11 +452,11 @@
 			AC_MSG_ERROR(No supported threads found!)
 		])
 		;;
 	esac
 
-	AC_DEFINE(OF_THREADS, 1, [Whether we have threads])
+	AC_DEFINE(OF_HAVE_THREADS, 1, [Whether we have threads])
 	AC_SUBST(USE_SRCS_THREADS, '${SRCS_THREADS}')
 	AC_SUBST(USE_INCLUDES_THREADS, '${INCLUDES_THREADS}')
 
 	AC_MSG_CHECKING(whether __thread works)
 	AC_TRY_LINK([
@@ -468,11 +468,11 @@
 		__thread int x = 0;
 	], [
 		x++;
 	], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(OF_COMPILER_TLS, 1, [Whether __thread works])
+		AC_DEFINE(OF_HAVE_COMPILER_TLS, 1, [Whether __thread works])
 	], [
 		AC_MSG_RESULT(no)
 	])
 
 	atomic_ops="none"
@@ -519,11 +519,11 @@
 	atomic_ops="not needed"
 ])
 
 AC_MSG_CHECKING(for atomic operations)
 AS_IF([test x"$atomic_ops" != x"none"], [
-	AC_DEFINE(OF_ATOMIC_OPS, 1, [Whether we have atomic operations])
+	AC_DEFINE(OF_HAVE_ATOMIC_OPS, 1, [Whether we have atomic operations])
 	AC_SUBST(ATOMIC_H, "atomic.h")
 ])
 AC_MSG_RESULT($atomic_ops)
 
 AC_CHECK_LIB(socket, socket, LIBS="$LIBS -lsocket")
@@ -544,11 +544,11 @@
 AC_CHECK_HEADER(poll.h, [
 	AC_DEFINE(HAVE_POLL_H, 1, [Whether we have poll.h])
 	AC_SUBST(OFSTREAMOBSERVER_POLL_M, "OFStreamObserver_poll.m")
 ])
 AC_CHECK_HEADERS(sys/select.h, [
-	AC_DEFINE(OF_HAVE_SYS_SELECT_H, 1, [Whether we have sys/select.h])
+	AC_DEFINE(HAVE_SYS_SELECT_H, 1, [Whether we have sys/select.h])
 	AC_SUBST(OFSTREAMOBSERVER_SELECT_M, "OFStreamObserver_select.m")
 ])
 case "$host_os" in
 	mingw*)
 		AC_SUBST(OFSTREAMOBSERVER_SELECT_M,