diff --git a/src/fensterPiepser_NodeMCU_32S.cpp b/src/fensterPiepser_NodeMCU_32S.cpp
index 3e248f8..4d9e413 100644
--- a/src/fensterPiepser_NodeMCU_32S.cpp
+++ b/src/fensterPiepser_NodeMCU_32S.cpp
@@ -132,7 +132,7 @@ Fenster* alleFenster[NUM_FENSTER] =
 #endif
 #endif
 
-uint32_t loopCountSincePause = 0u;
+volatile uint32_t loopCountSincePause = 0u;
 uint8_t toneRequest = 0u;
 
 /*---------------- LOCAL VARIABLES -------------  */