diff --git a/mach/pdp/libsys/compmodule b/mach/pdp/libsys/compmodule
index 32b04832a..ed9205478 100755
--- a/mach/pdp/libsys/compmodule
+++ b/mach/pdp/libsys/compmodule
@@ -1,4 +1,4 @@
-if pdp -O -c -I../../../h -I. $1 1>&2
+if pdp -O -P -c -I../../../h -I. $1 1>&2
 then echo `basename $1 $2`.o
 else exit 1
 fi