diff --git a/libraries/ESP8266WiFi/src/ESP8266WiFiGratuitous.cpp b/libraries/ESP8266WiFi/src/ESP8266WiFiGratuitous.cpp
index 0465fbc4f8..1ba3f862b5 100644
--- a/libraries/ESP8266WiFi/src/ESP8266WiFiGratuitous.cpp
+++ b/libraries/ESP8266WiFi/src/ESP8266WiFiGratuitous.cpp
@@ -72,6 +72,7 @@ bool ESP8266WiFiGratuitous::stationKeepAliveSetIntervalMs (uint32_t ms)
     if (_timer)
     {
         os_timer_disarm(_timer);
+        free(_timer);
         _timer = nullptr;
     }