diff --git a/doc/html/Makefile.in b/doc/html/Makefile.in
index 432973a2..ec7713f3 100644
--- a/doc/html/Makefile.in
+++ b/doc/html/Makefile.in
@@ -8,7 +8,11 @@ include $(MAGICDIR)/defs.mak
 HTML_INSTDIR=$(INSTALL_LIBDIR)/magic/doc/html
 
 install: $(DESTDIR)${HTML_INSTDIR}
-	tar -C $(srcdir) -cf - . | (cd $(DESTDIR)${HTML_INSTDIR}; tar xf - )
+	# Ship only the HTML content, not the build files.  $(srcdir) holds
+	# Makefile.in (always) and, for an in-tree build, the config.status-generated
+	# Makefile; excluding both keeps the install identical in-tree vs out-of-tree.
+	tar -C $(srcdir) --exclude=./Makefile --exclude=./Makefile.in -cf - . \
+	    | (cd $(DESTDIR)${HTML_INSTDIR}; tar xf - )
 
 $(DESTDIR)${HTML_INSTDIR}:
 	${SCRIPTS}/mkdirs $(DESTDIR)${HTML_INSTDIR}