Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -1041,24 +1041,28 @@
 				[Whether we have sched_yield()])
 		])
 
 		AC_CHECK_FUNCS(pthread_attr_getschedpolicy)
 
+		old_OBJCFLAGS="$OBJCFLAGS"
+		OBJCFLAGS="$OBJCFLAGS -Werror"
 		AC_MSG_CHECKING(for pthread_attr_setinheritsched)
 		AC_COMPILE_IFELSE([
 			AC_LANG_PROGRAM([
-				#include <spawn.h>
+				#include <pthread.h>
 			], [
-				pthread_attr_setinheritsched(NULL, 0);
+				pthread_attr_setinheritsched(
+				    (pthread_attr_t *)-1, 0);
 			])
 		], [
 			AC_MSG_RESULT(yes)
 			AC_DEFINE(HAVE_PTHREAD_ATTR_SETINHERITSCHED, 1,
 				[Whether we have pthread_attr_setinheritsched])
 		], [
 			AC_MSG_RESULT(no)
 		])
+		OBJCFLAGS="$old_OBJCFLAGS"
 
 		AC_CHECK_HEADERS(pthread_np.h, [], [], [#include <pthread.h>])
 		AC_CHECK_FUNCS(pthread_set_name_np pthread_setname_np, break)
 		;;
 	esac