diff --git a/mail/courier/Makefile b/mail/courier/Makefile
index b58ba9b91f43..092dca1e7e2a 100644
--- a/mail/courier/Makefile
+++ b/mail/courier/Makefile
@@ -299,6 +299,10 @@ post-patch:
 		${WRKSRC}/courier/perms.sh.in
 	@${REINPLACE_CMD} '/^courieresmtp_LDADD =/s/$$/ -lcourierauth/' \
 		${WRKSRC}/courier/module.esmtp/Makefile.in
+# Avoid conflict with C++20 <version> by adding .txt suffix
+	@${REINPLACE_CMD} -i .c++20 's/>version$$/&.txt/' ${WRKSRC}/configure
+	@${FIND} ${WRKSRC} -name configure -exec ${REINPLACE_CMD} \
+		-i .c++20 '/^version.*cat/s,/version,&.txt,' {} +
 
 post-build:
 	@${PERL} -pi -e 's|^(auth)\s+(required).*|$$1\t\t$$2\tpam_unix.so\ttry_first_pass|g;' \