diff --git a/e_os.h b/e_os.h
index 0c0784f9a97274d9056d7983f0f8727e78083735..4f9c983ef18475bece8782e45e30768f5aed1c81 100644
--- a/e_os.h
+++ b/e_os.h
@@ -355,12 +355,14 @@ extern HINSTANCE _hInstance;
 #    if defined(VMS) && !defined(__DECC)
 #      include <socket.h>
 #      include <in.h>
+#      include <inet.h>
 #    else
 #      include <sys/socket.h>
 #      ifdef FILIO_H
 #        include <sys/filio.h> /* Added for FIONBIO under unixware */
 #      endif
 #      include <netinet/in.h>
+#      include <arpa/inet.h>
 #    endif
 
 #    if defined(NeXT) || defined(_NEXT_SOURCE)