diff --git a/devel/rubygem-rdoc/Makefile b/devel/rubygem-rdoc/Makefile
index 2d1d22e02f4d..7f935635245c 100644
--- a/devel/rubygem-rdoc/Makefile
+++ b/devel/rubygem-rdoc/Makefile
@@ -1,37 +1,39 @@
 PORTNAME=	rdoc
-PORTVERSION=	6.3.3
+PORTVERSION=	6.4.0
 CATEGORIES=	devel rubygems
 MASTER_SITES=	RG
 
 MAINTAINER=	ruby@FreeBSD.org
 COMMENT=	RDoc produces HTML and command-line documentation for Ruby projects
 
 LICENSE=	GPLv2 RUBY
 LICENSE_COMB=	dual
 LICENSE_FILE_RUBY=	${WRKSRC}/LICENSE.rdoc
 
+RUN_DEPENDS=	rubygem-psych>=4.0.0:textproc/rubygem-psych
+
 USES=		cpe gem
 USE_RUBY=	yes
 
 NO_ARCH=	yes
 
 CPE_VENDOR=	ruby-lang
 
 .include <bsd.port.pre.mk>
 
 .if ${RUBY_VER} >= 2.7
 PLIST_FILES=	bin/rdoc bin/ri share/man/man1/ri.1.gz
 
 post-install:
 	${MKDIR} ${STAGEDIR}${PREFIX}/share/man/man1
 	${INSTALL_DATA} ${WRKSRC}/man/ri.1 ${STAGEDIR}${PREFIX}/share/man/man1
 
 .elif ${RUBY_VER} == 2.6
 # WIP: rdoc wrapper script is installed by ruby port so far, see bug 241554, 237833
 post-install:
 	${RM} ${STAGEDIR}${PREFIX}/bin/rdoc ${STAGEDIR}${PREFIX}/bin/ri
 .else
 IGNORE=		${PORTNAME} is included in ${RUBY_PORT}
 .endif
 
 .include <bsd.port.post.mk>
diff --git a/devel/rubygem-rdoc/distinfo b/devel/rubygem-rdoc/distinfo
index 20f5249efb4a..621fc40787ff 100644
--- a/devel/rubygem-rdoc/distinfo
+++ b/devel/rubygem-rdoc/distinfo
@@ -1,3 +1,3 @@
-TIMESTAMP = 1636622683
-SHA256 (rubygem/rdoc-6.3.3.gem) = 5bd7010d76e259794f24713d5650406611854226bb6186460b49d3229bd74635
-SIZE (rubygem/rdoc-6.3.3.gem) = 569344
+TIMESTAMP = 1640394263
+SHA256 (rubygem/rdoc-6.4.0.gem) = 5e3f949c52db3e1361ab14b1672ae284254cd40eff2df0fbb361d5bcfb66bfaf
+SIZE (rubygem/rdoc-6.4.0.gem) = 647168