diff --git a/mach/pmds/cv/Makefile b/mach/pmds/cv/Makefile
index d7308871d..88eac1cb4 100644
--- a/mach/pmds/cv/Makefile
+++ b/mach/pmds/cv/Makefile
@@ -3,6 +3,14 @@ CFLAGS=-O
 pmcv:		pmcv.o
 		$(CC) -o pmcv -n pmcv.o
 
+pmcv.c:
+		case `ack_sys` in \
+		vax*)	cp vax_cv.c pmcv.c ;; \
+		pdp*)	cp pdp_cv.c pmcv.c ;; \
+		*)	echo "A conversion program should be present in `pwd`/pmcv.c" ;\
+			exit 9 ;; \
+		esac
+
 install:	ins_pmcv
 ins_pmcv:	pmcv
 		../../install pmcv