Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -11,11 +11,11 @@
 
 CFLAGS="$CFLAGS -Wall"
 AX_CHECK_COMPILER_FLAGS(-pipe, [CFLAGS="$CFLAGS -pipe"])
 AX_CHECK_COMPILER_FLAGS(-fno-common, [CFLAGS="$CFLAGS -fno-common"])
 
-AC_DEFINE(OF_CONFIG_H, 1, [Define so that we know we got our config.h])
+AC_DEFINE(OF_CONFIGURED, 1, [Define so that we know we got our config.h])
 
 BUILDSYS_LIB
 AC_DEFINE_UNQUOTED(PLUGIN_SUFFIX, "$PLUGIN_SUFFIX", [Suffix for plugins])
 if test x"$PLUGIN_SUFFIX" != "x"; then
 	AC_SUBST(OFPLUGIN_M, "OFPlugin.m")

Index: objfw-config.in
==================================================================
--- objfw-config.in
+++ objfw-config.in
@@ -1,11 +1,12 @@
 #!/bin/sh
 prefix="@prefix@"
 exec_prefix="@exec_prefix@"
 libdir="@libdir@"
 CFLAGS=""
-CPPFLAGS="-I@includedir@ @ENDIANESS_DEF@ @ASPRINTF_DEF@ @OFPLUGIN_DEF@"
+CPPFLAGS="-I@includedir@ -DOF_CONFIGURED @ENDIANESS_DEF@ @ASPRINTF_DEF@"
+CPPFLAGS="$CPPFLAGS @OFPLUGIN_DEF@"
 CXXFLAGS=""
 OBJCFLAGS="-fobjc-exceptions -fconstant-string-class=OFConstString"
 OBJCFLAGS="$OBJCFLAGS @NO_CONST_CFSTRINGS@"
 LDFLAGS="@RPATH_LDFLAGS@"
 LIBS="-L${libdir} -lobjfw @LIBS@"

Index: src/OFMacros.h
==================================================================
--- src/OFMacros.h
+++ src/OFMacros.h
@@ -6,10 +6,15 @@
  *
  * This file is part of libobjfw. It may be distributed under the terms of the
  * Q Public License 1.0, which can be found in the file LICENSE included in
  * the packaging of this file.
  */
+
+#ifndef OF_CONFIGURED
+#error You are missing the libobjfw definitions!
+#error Please use objfw-config!
+#endif
 
 #ifdef __GNUC__
 #define OF_INLINE inline __attribute__((always_inline))
 #define OF_LIKELY(cond) __builtin_expect(!!(cond), 1)
 #define OF_UNLIKELY(cond) __builtin_expect(!!(cond), 0)

Index: src/OFObject.h
==================================================================
--- src/OFObject.h
+++ src/OFObject.h
@@ -6,10 +6,15 @@
  *
  * This file is part of libobjfw. It may be distributed under the terms of the
  * Q Public License 1.0, which can be found in the file LICENSE included in
  * the packaging of this file.
  */
+
+#ifndef OF_CONFIGURED
+#error You are missing the libobjfw definitions!
+#error Please use objfw-config!
+#endif
 
 #include <stddef.h>
 #include <stdint.h>
 
 #import <objc/objc.h>

Index: src/asprintf.h
==================================================================
--- src/asprintf.h
+++ src/asprintf.h
@@ -6,12 +6,17 @@
  *
  * This file is part of libobjfw. It may be distributed under the terms of the
  * Q Public License 1.0, which can be found in the file LICENSE included in
  * the packaging of this file.
  */
+
+#ifndef OF_CONFIGURED
+#error You are missing the libobjfw definitions!
+#error Please use objfw-config!
+#endif
 
 #ifndef OF_HAVE_ASPRINTF
 #include <stdarg.h>
 
 extern int asprintf(char**, const char*, ...);
 extern int vasprintf(char**, const char*, va_list);
 #endif

Index: tests/objc_sync/objc_sync.m
==================================================================
--- tests/objc_sync/objc_sync.m
+++ tests/objc_sync/objc_sync.m
@@ -1,5 +1,18 @@
+/*
+ * Copyright (c) 2008 - 2009
+ *   Jonathan Schleifer <js@webkeks.org>
+ *
+ * All rights reserved.
+ *
+ * This file is part of libobjfw. It may be distributed under the terms of the
+ * Q Public License 1.0, which can be found in the file LICENSE included in
+ * the packaging of this file.
+ */
+
+#include "config.h"
+
 #include <stdio.h>
 
 #import "OFString.h"
 #import "OFThread.h"