diff --git a/solenv/gbuild/platform/solaris.mk b/solenv/gbuild/platform/solaris.mk
index 8d394754e5b4..0e394dc4ce8f 100755
--- a/solenv/gbuild/platform/solaris.mk
+++ b/solenv/gbuild/platform/solaris.mk
@@ -49,6 +49,7 @@ gb_OSDEFS := \
 
 gb_COMPILERDEFS := \
 	-D$(COM) \
+	-DCPPU_ENV=sunpro5 \
 #	-D$(CVER) \
 #	-DCVER=$(CVER) \