diff --git a/src/include/port/bsdi.h b/src/include/port/bsdi.h
index f4865361132a605720c77c20a443b6f22da98403..e5ba051f239b6168c397e6d0e7638a0013600e57 100644
--- a/src/include/port/bsdi.h
+++ b/src/include/port/bsdi.h
@@ -8,3 +8,8 @@
 #define HAS_TEST_AND_SET
 
 typedef unsigned char slock_t;
+
+/* This is marked as obsoleted in BSD/OS 4.3. */
+#ifndef EAI_ADDRFAMILY
+#define  EAI_ADDRFAMILY		1
+#endif