diff --git a/core/src/main/java/hudson/PluginWrapper.java b/core/src/main/java/hudson/PluginWrapper.java
index 2860181482..b9cdd610db 100644
--- a/core/src/main/java/hudson/PluginWrapper.java
+++ b/core/src/main/java/hudson/PluginWrapper.java
@@ -35,6 +35,7 @@ import hudson.model.UpdateSite;
 import hudson.util.VersionNumber;
 import jenkins.YesNoMaybe;
 import jenkins.model.Jenkins;
+import jenkins.util.java.JavaUtils;
 import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.LogFactory;
 import org.kohsuke.accmod.Restricted;
@@ -762,8 +763,7 @@ public class PluginWrapper implements Comparable<PluginWrapper>, ModelObject {
 
             String minimumJavaVersion = getMinimumJavaVersion();
             if (minimumJavaVersion != null) {
-                // TODO replace with calls to Runtime.version() once we're on Java 9+
-                VersionNumber actualVersion = new VersionNumber(System.getProperty("java.specification.version"));
+                VersionNumber actualVersion = JavaUtils.getCurrentJavaRuntimeVersionNumber();
                 if (actualVersion.isOlderThan(new VersionNumber(minimumJavaVersion))) {
                     versionDependencyError(Messages.PluginWrapper_obsoleteJava(actualVersion.toString(), minimumJavaVersion), actualVersion.toString(), minimumJavaVersion);
                 }
diff --git a/core/src/main/java/hudson/model/UpdateSite.java b/core/src/main/java/hudson/model/UpdateSite.java
index 89ae58d46b..739229faa8 100644
--- a/core/src/main/java/hudson/model/UpdateSite.java
+++ b/core/src/main/java/hudson/model/UpdateSite.java
@@ -70,6 +70,7 @@ import jenkins.model.DownloadSettings;
 import jenkins.security.UpdateSiteWarningsConfiguration;
 import jenkins.util.JSONSignatureValidator;
 import jenkins.util.SystemProperties;
+import jenkins.util.java.JavaUtils;
 import net.sf.json.JSONArray;
 import net.sf.json.JSONException;
 import net.sf.json.JSONObject;
@@ -1132,8 +1133,9 @@ public class UpdateSite {
          */
         public boolean isForNewerJava() {
             try {
+                final VersionNumber currentRuntimeJavaVersion = JavaUtils.getCurrentJavaRuntimeVersionNumber();
                 return minimumJavaVersion != null && new VersionNumber(minimumJavaVersion).isNewerThan(
-                        new VersionNumber(System.getProperty("java.specification.version")));
+                        currentRuntimeJavaVersion);
             } catch (NumberFormatException nfe) {
                 logBadMinJavaVersion();
                 return false; // treat this as undeclared minimum Java version
diff --git a/core/src/main/java/jenkins/util/java/JavaUtils.java b/core/src/main/java/jenkins/util/java/JavaUtils.java
index 909c3e8457..38a28e72c0 100644
--- a/core/src/main/java/jenkins/util/java/JavaUtils.java
+++ b/core/src/main/java/jenkins/util/java/JavaUtils.java
@@ -23,6 +23,7 @@
  */
 package jenkins.util.java;
 
+import hudson.util.VersionNumber;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
 
@@ -42,7 +43,7 @@ public class JavaUtils {
      * @return {@code true} if it is Java 8 or older version
      */
     public static boolean isRunningWithJava8OrBelow() {
-        String javaVersion = System.getProperty("java.specification.version");
+        String javaVersion = getCurrentRuntimeJavaVersion();
         return javaVersion.startsWith("1.");
     }
 
@@ -51,8 +52,23 @@ public class JavaUtils {
      * @return {@code true} if it is Java 9 or above
      */
     public static boolean isRunningWithPostJava8() {
-        String javaVersion = System.getProperty("java.specification.version");
+        String javaVersion = getCurrentRuntimeJavaVersion();
         return !javaVersion.startsWith("1.");
     }
 
+    /**
+     * Returns the JVM's current version as a {@link VersionNumber} instance.
+     */
+    public static VersionNumber getCurrentJavaRuntimeVersionNumber() {
+        return new VersionNumber(getCurrentRuntimeJavaVersion());
+    }
+
+    /**
+     * Returns the JVM's current version as a {@link String}.
+     * @see System#getProperty(String)
+     */
+    public static String getCurrentRuntimeJavaVersion() {
+        // TODO: leverage Runtime.version() once on Java 9+
+        return System.getProperty("java.specification.version");
+    }
 }