diff --git a/Make.inc.in b/Make.inc.in
index ad88c3d4..1fa3179c 100755
--- a/Make.inc.in
+++ b/Make.inc.in
@@ -38,6 +38,7 @@ EXTRA_COBJS=@FAKEMPI@
 
 PSBFDEFINES=@FDEFINES@
 PSBCDEFINES=@CDEFINES@
+PSBCXXDEFINES=@CDEFINES@
 AR=@AR@
 RANLIB=@RANLIB@