diff --git a/GNUmakefile b/GNUmakefile
index 5f7cc6f..e3eeb82 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -115,7 +115,7 @@ iopause.h select.h havekqueue.h haveepoll.h libepoll Makefile
 
 INCLUDES=buffer.h byte.h fmt.h ip4.h ip6.h mmap.h scan.h socket.h str.h stralloc.h \
 uint16.h uint32.h uint64.h open.h textcode.h tai.h taia.h dns.h iopause.h case.h \
-openreadclose.h readclose.h ndelay.h array.h io.h safemult.h
+openreadclose.h readclose.h ndelay.h array.h io.h safemult.h iob.h
 
 install: libowfat.a
 	install -d $(INCLUDEDIR) $(MAN3DIR) $(LIBDIR)