diff --git a/.ruby-version b/.ruby-version
index 860487ca..2c9b4ef4 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.7.1
+2.7.3
diff --git a/Dockerfile b/Dockerfile
index 5fe323f8..6b84ef29 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-ARG RUBY_VERSION=2.7.1
+ARG RUBY_VERSION=2.7.3
 FROM ruby:$RUBY_VERSION
 
 RUN apt-get update \
diff --git a/Dockerfile.alpine b/Dockerfile.alpine
index 92024347..3c572c2f 100644
--- a/Dockerfile.alpine
+++ b/Dockerfile.alpine
@@ -1,4 +1,4 @@
-FROM ruby:2.7.1-alpine
+FROM ruby:2.7.3-alpine
 
 RUN apk update && apk add --no-cache \
   git
diff --git a/script/cibuild-docker b/script/cibuild-docker
index 37909b1b..7a6ca87d 100755
--- a/script/cibuild-docker
+++ b/script/cibuild-docker
@@ -3,7 +3,7 @@
 set -ex
 
 # Set the ruby version in the Action definition matrix.
-: "${RUBY_VERSION:="2.7.1"}"
+: "${RUBY_VERSION:="2.7.3"}"
 
 docker build --build-arg "RUBY_VERSION=$RUBY_VERSION" -t github-pages .
 docker run --rm --workdir /src/gh/pages-gem github-pages script/cibuild