diff --git a/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/execution/ExecutionService.java b/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/execution/ExecutionService.java
index cf7ef56d296..9a936010758 100644
--- a/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/execution/ExecutionService.java
+++ b/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/execution/ExecutionService.java
@@ -109,7 +109,7 @@ public class ExecutionService extends AbstractComponent {
         this.indexDefaultTimeout = settings.getAsTime("xpack.watcher.internal.ops.index.default_timeout", TimeValue.timeValueSeconds(30));
     }
 
-    public void start() throws Exception {
+    public synchronized void start() throws Exception {
         if (started.get()) {
             return;
         }
@@ -133,7 +133,7 @@ public class ExecutionService extends AbstractComponent {
         return triggeredWatchStore.validate(state) && HistoryStore.validate(state);
     }
 
-    public void stop() {
+    public synchronized void stop() {
         if (started.compareAndSet(true, false)) {
             logger.debug("stopping execution service");
             // We could also rely on the shutdown in #updateSettings call, but
@@ -541,7 +541,7 @@ public class ExecutionService extends AbstractComponent {
      * This clears out the current executions and sets new empty current executions
      * This is needed, because when this method is called, watcher keeps running, so sealing executions would be a bad idea
      */
-    public void clearExecutions() {
+    public synchronized void clearExecutions() {
         currentExecutions.sealAndAwaitEmpty(maxStopTimeout);
         currentExecutions = new CurrentExecutions();
     }