--- a/Makefile.in
+++ b/Makefile.in
@@ -703,7 +703,7 @@
 update_mans = \
   $(AM_V_GEN): \
     && $(MKDIR_P) doc \
-    && ./pre-inst-env $(PERL) $(srcdir)/doc/help2man --output=$@
+    && ./pre-inst-env $(PERL) $(srcdir)/doc/help2man --output=$@ --no-discard-stderr
 
 checklinkx = $(top_srcdir)/contrib/checklinkx
 # that 4-second sleep seems to be what gnu.org likes.