diff --git a/pom.xml b/pom.xml
index b463dde..83aa304 100644
--- a/pom.xml
+++ b/pom.xml
@@ -108,7 +108,7 @@
     </commons.scmPubUrl>
     <commons.scmPubCheckoutDirectory>site-content</commons.scmPubCheckoutDirectory>
     <checkstyle.plugin.version>3.1.2</checkstyle.plugin.version>
-    <checkstyle.version>9.0.1</checkstyle.version>
+    <checkstyle.version>9.1</checkstyle.version>
     <maven-scm.version>1.12.0</maven-scm.version>
     <commons.spotbugs.version>4.4.2.2</commons.spotbugs.version>
     <commons.spotbugs.impl.version>4.4.2</commons.spotbugs.impl.version>    
diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index a2f52f4..3d65e22 100755
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -44,7 +44,7 @@
       <action type="update" dev="ggregory">Update JUnit from 4.12 to 4.13.2, #23 #39.</action>
       <action type="update" dev="kinow" due-to="Gary Gregory, Dependabot">Bump maven.dependency.version from 3.6.1 to 3.8.3 #47 #76.</action>
       <action type="update" dev="ggregory">Update commons-io:commons-io from 2.6 to 2.11.0 #13 #63.</action>
-      <action type="update" dev="ggregory">Update checkstyle from 8.34 to 9.0.1 #5 #12 #14 #27 #31 #35 #40 #46 #53 #58 #64 #65 #69 #77.</action>
+      <action type="update" dev="ggregory">Update checkstyle from 8.34 to 9.1 #5 #12 #14 #27 #31 #35 #40 #46 #53 #58 #64 #65 #69 #77 #84.</action>
       <action type="update" dev="ggregory">Update actions/checkout from v2.3.1 to v2.3.5 #8, #16, #28, #78.</action>
       <action type="update" dev="ggregory">Update velocity-engine-core from 2.1 to 2.3 #4 #43.</action>
       <action type="update" dev="ggregory">Update commons-codec from 1.13 to 1.15.</action>