diff --git a/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/filewatch/FileSystemWatcher.java b/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/filewatch/FileSystemWatcher.java
index c3530b3b7f..9c44a4e0d3 100644
--- a/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/filewatch/FileSystemWatcher.java
+++ b/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/filewatch/FileSystemWatcher.java
@@ -194,7 +194,7 @@ public class FileSystemWatcher {
 			}
 			this.watchThread = null;
 		}
-		if (Thread.currentThread() != thread) {
+		if (thread != null && Thread.currentThread() != thread) {
 			try {
 				thread.join();
 			}