diff --git a/lib/sun2/descr b/lib/sun2/descr
index 53c8e88b..b6be587b 100644
--- a/lib/sun2/descr
+++ b/lib/sun2/descr
@@ -12,7 +12,7 @@ var LIB=lib/{P}/tail_
 var RT=lib/{P}/head_
 var PLIB=lib/{M}/tail_
 var PRT=lib/{M}/head_
-var CPP_F=-Dunix=unix
+var CPP_F=-Dunix=unix -D__BSD4_2
 var INCLUDES=-I{EM}/include/_tail_cc
 # 413 align is the default, rom in text
 var ALIGN=-a0:2 -a1:2 -a2:0x20000 -a3:2 -b0:0x2020
diff --git a/lib/sun3/descr b/lib/sun3/descr
index d9996fa9..4b932886 100644
--- a/lib/sun3/descr
+++ b/lib/sun3/descr
@@ -12,7 +12,7 @@ var LIB=lib/{P}/tail_
 var RT=lib/{P}/head_
 var PLIB=lib/{M}/tail_
 var PRT=lib/{M}/head_
-var CPP_F=-Dunix=unix
+var CPP_F=-Dunix=unix -D__BSD4_2
 var INCLUDES=-I{EM}/include/_tail_cc
 # 413 align is the default, rom in text
 var ALIGN=-a0:2 -a1:2 -a2:0x20000 -a3:2 -b0:0x2020