diff --git a/asciidoctorj-diagram/gradle.properties b/asciidoctorj-diagram/gradle.properties
index f9030b611..aa74a5082 100644
--- a/asciidoctorj-diagram/gradle.properties
+++ b/asciidoctorj-diagram/gradle.properties
@@ -1,3 +1,3 @@
 properName=AsciidoctorJ Diagram
 description=AsciidoctorJ Diagram bundles the Asciidoctor Diagram RubyGem (asciidoctor-diagram) so it can be loaded into the JVM using JRuby.
-version=1.3.0
+version=1.3.1
diff --git a/build.gradle b/build.gradle
index ee007c30e..02bcf70b7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -31,7 +31,7 @@ ext {
   guavaVersion = '18.0'
   hamcrestVersion = '1.3'
   jcommanderVersion = '1.35'
-  jrubyVersion = '1.7.22'
+  jrubyVersion = '1.7.21'
   jsoupVersion = '1.8.3'
   junitVersion = '4.12'
   saxonVersion = '9.5.1-6'
@@ -162,6 +162,7 @@ configure(subprojects.findAll { !it.name.endsWith('-distribution') }) {
   jruby {
     defaultRepositories = false
     defaultVersion = jrubyVersion
+    execVersion = jrubyVersion
     // TODO I'd like to be able to customize the name of the gemInstallDir
   }