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
@@ -1,5 +1,5 @@
 PORTNAME=	rdoc
-PORTVERSION=	6.3.3
+PORTVERSION=	6.4.0
 CATEGORIES=	devel rubygems
 MASTER_SITES=	RG
 
@@ -10,6 +10,8 @@ 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
 
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