issue5545: Switch to Autoconf for multiprocessing; special thanks to Martin Lowis for help
diff --git a/Modules/_multiprocessing/multiprocessing.h b/Modules/_multiprocessing/multiprocessing.h
index 4f4f9d7..f6ab994 100644
--- a/Modules/_multiprocessing/multiprocessing.h
+++ b/Modules/_multiprocessing/multiprocessing.h
@@ -27,7 +27,7 @@
# include <sys/socket.h>
# include <sys/uio.h>
# include <arpa/inet.h> /* htonl() and ntohl() */
-# if HAVE_SEM_OPEN
+# ifdef HAVE_SEM_OPEN
# include <semaphore.h>
typedef sem_t *SEM_HANDLE;
# endif