diff --git a/jason-interpreter/src/main/java/jason/asSemantics/Agent.java b/jason-interpreter/src/main/java/jason/asSemantics/Agent.java
index f70b1854..5be6e2e2 100644
--- a/jason-interpreter/src/main/java/jason/asSemantics/Agent.java
+++ b/jason-interpreter/src/main/java/jason/asSemantics/Agent.java
@@ -35,6 +35,8 @@
 import java.util.*;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -707,7 +709,8 @@ public List<Option> relevantPlans(Trigger teP, Event evt) throws JasonException
     }
 
     public List<Option> applicablePlans(List<Option> rp) throws JasonException {
-        synchronized (getTS().getC().syncApPlanSense) {
+        getTS().getC().syncApPlanSense.lock();
+        try {
             List<Option> ap = null;
             if (rp != null) {
                 for (Option opt: rp) {
@@ -750,6 +753,8 @@ public List<Option> applicablePlans(List<Option> rp) throws JasonException {
                 }
             }
             return ap;
+        } finally {
+            getTS().getC().syncApPlanSense.unlock();
         }
     }
 
@@ -1135,8 +1140,9 @@ public boolean hasCustomSelectOption() {
     static DocumentBuilder builder = null;
 
 
+    private Lock agStateLock = new ReentrantLock();
     /** Gets the agent "mind" (beliefs, plans, and circumstance) as XML */
-    public synchronized Document getAgState() {
+    public Document getAgState() {
         if (builder == null) {
             try {
                 builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
@@ -1148,11 +1154,16 @@ public synchronized Document getAgState() {
         Document docDOM = builder.newDocument();
         docDOM.appendChild(docDOM.createProcessingInstruction("xml-stylesheet", "href='http://jason.sf.net/xml/agInspection.xsl' type='text/xsl' "));
 
-        Element ag = getAsDOM(docDOM);
-        docDOM.appendChild(ag);
+        agStateLock.lock();
+        try {
+            Element ag = getAsDOM(docDOM);
+            docDOM.appendChild(ag);
 
-        ag.appendChild(ts.getC().getAsDOM(docDOM));
-        return docDOM;
+            ag.appendChild(ts.getC().getAsDOM(docDOM));
+            return docDOM;
+        } finally {
+            agStateLock.unlock();
+        }
     }
 
     @Override
diff --git a/jason-interpreter/src/main/java/jason/asSemantics/Circumstance.java b/jason-interpreter/src/main/java/jason/asSemantics/Circumstance.java
index 9f4b8e4f..f0a0f9fa 100644
--- a/jason-interpreter/src/main/java/jason/asSemantics/Circumstance.java
+++ b/jason-interpreter/src/main/java/jason/asSemantics/Circumstance.java
@@ -55,10 +55,9 @@ public class Circumstance implements Serializable, ToDOM {
 
     private TransitionSystem ts = null;
 
-    public transient Object syncApPlanSense = new Object();
+    public  Lock syncApPlanSense = new ReentrantLock();
 
     public Circumstance() {
-        syncApPlanSense = new Object();
         create();
         reset();
     }
@@ -74,9 +73,9 @@ public void resetIntentionsWithGoalCondition() {
     }
 
 
+    @Serial
     private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
         inputStream.defaultReadObject();
-        syncApPlanSense = new Object();
     }
 
     public void setTS(TransitionSystem ts) {
diff --git a/jason-interpreter/src/main/java/jason/asSemantics/TransitionSystem.java b/jason-interpreter/src/main/java/jason/asSemantics/TransitionSystem.java
index 283307f4..bdedc7ff 100644
--- a/jason-interpreter/src/main/java/jason/asSemantics/TransitionSystem.java
+++ b/jason-interpreter/src/main/java/jason/asSemantics/TransitionSystem.java
@@ -1662,8 +1662,11 @@ public void sense() {
 
             if (nrcslbr >= setts.nrcbp()) {
                 nrcslbr = 0;
-                synchronized (C.syncApPlanSense) {
+                C.syncApPlanSense.lock();
+                try {
                     ag.buf(getAgArch().perceive());
+                } finally {
+                    C.syncApPlanSense.unlock();
                 }
                 getAgArch().checkMail();
             }