@@ -194,25 +194,10 @@
 ], [
 	AC_MSG_RESULT(no)
 	AC_MSG_ERROR(Compiler does not support properties!)
 ])
 
-AC_MSG_CHECKING(whether Objective C compiler supports blocks)
-old_OBJCFLAGS="$OBJCFLAGS"
-OBJCFLAGS="$OBJCFLAGS -fblocks"
-AC_TRY_COMPILE([], [
-	int (^foo)(int bar);
-	foo = ^ (int bar) { return 0; }
-], [
-	AC_SUBST(BLOCKS_FLAGS, "-fblocks")
-	AC_SUBST(OFBLOCKTESTS_M, "OFBlockTests.m")
-	AC_MSG_RESULT(yes)
-], [
-	AC_MSG_RESULT(no)
-	OBJCFLAGS="$old_OBJCFLAGS"
-])
-
 AC_CHECK_TOOL(AR, ar)
 AC_PROG_RANLIB
 AC_ARG_ENABLE(shared,
 	AS_HELP_STRING([--disable-shared], [do not build shared library]))
 AS_IF([test x"$enable_shared" != x"no"], [
@@ -1191,10 +1176,11 @@
 		;;
 	*-*-msdosdjgpp*)
 		have_processes="no"
 		;;
 	*)
+		AC_HEADER_SYS_WAIT
 		AC_CHECK_FUNCS(kill)
 
 		AC_CHECK_FUNC(posix_spawnp, [
 			AS_IF([test x"$ac_cv_func_kill" = x"yes"], [
 				have_processes="yes"
@@ -1241,10 +1227,28 @@
 		    -o x"$enable_shared" = x"no"], [
 			AC_SUBST(OBJFW_BRIDGE_STATIC_LIB, "libobjfw-bridge.a")
 		])
 	])
 ])
+
+dnl This needs to be after all other header checks, as they include unistd.h,
+dnl which in old glibc versions uses __block. This is worked around in the code
+dnl by undefining __USE_XOPEN.
+AC_MSG_CHECKING(whether Objective C compiler supports blocks)
+old_OBJCFLAGS="$OBJCFLAGS"
+OBJCFLAGS="$OBJCFLAGS -fblocks"
+AC_TRY_COMPILE([], [
+	int (^foo)(int bar);
+	foo = ^ (int bar) { return 0; }
+], [
+	AC_SUBST(BLOCKS_FLAGS, "-fblocks")
+	AC_SUBST(OFBLOCKTESTS_M, "OFBlockTests.m")
+	AC_MSG_RESULT(yes)
+], [
+	AC_MSG_RESULT(no)
+	OBJCFLAGS="$old_OBJCFLAGS"
+])
 
 AS_IF([test x"$GOBJC" = x"yes"], [
 	OBJCFLAGS="$OBJCFLAGS -Wwrite-strings -Wpointer-arith -Werror"
 
 	AC_MSG_CHECKING(whether we need -Wno-strict-aliasing due to GCC bugs)
@@ -1280,11 +1284,11 @@
 		{
 			struct objc_class *_isa;
 			Foo *_foo;
 		}
 
-		@property (readonly, retain) Foo *foo;
+		@property (readonly, nonatomic) Foo *foo;
 
 		+ (Foo *)foo;
 		@end
 
 		@implementation Foo
@@ -1355,10 +1359,21 @@
 		- (void)dealloc;
 		@end
 
 		@interface Foo: Object
 		@end
+
+		void
+		test(void)
+		{
+			if (sizeof(int) == 4)
+				__asm__ ("");
+			else if (sizeof(int) == 8)
+				__asm__ ("");
+			else
+				abort();
+		}
 
 		/*
 		 * Unfortunately, this cannot be shorter, as it only works when
 		 * it is used inside a macro.
 		 */