diff --git a/mach/vax4/libbc/Makefile b/mach/vax4/libbc/Makefile
index 1573b6da..c3b833f0 100644
--- a/mach/vax4/libbc/Makefile
+++ b/mach/vax4/libbc/Makefile
@@ -9,7 +9,6 @@ install:
 
 cmp:
 	make -f $(MAKEFILE) $(BCDEF) $(MACHDEF) tail
-	-../../compare head_bc
 	-../../compare tail_bc
 
 clean:
diff --git a/mach/vax4/libbc/compmodule b/mach/vax4/libbc/compmodule
index 491f6d25..6327cb99 100755
--- a/mach/vax4/libbc/compmodule
+++ b/mach/vax4/libbc/compmodule
@@ -1,2 +1,6 @@
-${MACH?} -I../../../h ${MACHFL?} $1 1>&2
-echo `basename $1 $2`.o
+if ${MACH?} -I../../../h ${MACHFL?} $1 1>&2
+then
+	echo `basename $1 $2`.o
+else
+	exit 1
+fi
diff --git a/mach/vax4/libpc/compmodule b/mach/vax4/libpc/compmodule
index 491f6d25..6327cb99 100755
--- a/mach/vax4/libpc/compmodule
+++ b/mach/vax4/libpc/compmodule
@@ -1,2 +1,6 @@
-${MACH?} -I../../../h ${MACHFL?} $1 1>&2
-echo `basename $1 $2`.o
+if ${MACH?} -I../../../h ${MACHFL?} $1 1>&2
+then
+	echo `basename $1 $2`.o
+else
+	exit 1
+fi