diff --git a/src/main/org/apache/tools/ant/AntClassLoader.java b/src/main/org/apache/tools/ant/AntClassLoader.java
index 0e9b941b3..d44cc0a81 100644
--- a/src/main/org/apache/tools/ant/AntClassLoader.java
+++ b/src/main/org/apache/tools/ant/AntClassLoader.java
@@ -526,7 +526,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener {
      * @param isolated Whether or not this classloader should run in
      *                 isolated mode.
      */
-    public void setIsolated(boolean isolated) {
+    public synchronized void setIsolated(boolean isolated) {
         ignoreBase = isolated;
     }
 
diff --git a/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java b/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java
index d8a534e1f..87847c246 100644
--- a/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java
+++ b/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java
@@ -237,7 +237,7 @@ public class ExecuteJava implements Runnable, TimeoutObserver {
     /**
      * @since 1.19, Ant 1.5
      */
-    public boolean killedProcess() {
+    public synchronized boolean killedProcess() {
         return timedOut;
     }
 }