diff --git a/GUI/xephem/Makefile b/GUI/xephem/Makefile
index 6fa4405..33d5085 100644
--- a/GUI/xephem/Makefile
+++ b/GUI/xephem/Makefile
@@ -192,7 +192,7 @@ xephem: $(INCS) $(OBJS)
 	$(CC) $(LDFLAGS) -o $@ $(OBJS) $(LIBS)
 
 xephem.1: xephem.man
-	nroff -man $? > $@
+	mandoc $? > $@
 
 libs:
 	cd ../../libastro; make