diff --git a/mac/otnet.c b/mac/otnet.c
index 1033961d..06fbea2b 100644
--- a/mac/otnet.c
+++ b/mac/otnet.c
@@ -6,6 +6,7 @@
 #define OTCARBONAPPLICATION 1
 #endif
 
+#include <Files.h> /* Needed by OpenTransportInternet.h */
 #include <OpenTransport.h>
 #include <OpenTptInternet.h>