diff --git a/app/src/main/java/me/micrusa/amaztimer/button/buttonListener.java b/app/src/main/java/me/micrusa/amaztimer/button/buttonListener.java
index 948358d3..5e3c4e95 100644
--- a/app/src/main/java/me/micrusa/amaztimer/button/buttonListener.java
+++ b/app/src/main/java/me/micrusa/amaztimer/button/buttonListener.java
@@ -167,7 +167,7 @@ public void stop() {
             executor = null;
             listening = false;
         }
-        if (wakeLock.isHeld())
+        if (wakeLock != null && wakeLock.isHeld())
             wakeLock.release();
     }