diff --git a/platformio.ini b/platformio.ini
index 518aaf2b..4973a892 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -26,7 +26,7 @@ description = Paxcounter is a proof-of-concept ESP32 device for metering passeng
 
 [common]
 ; for release_version use max. 10 chars total, use any decimal format like "a.b.c"
-release_version = 1.5.3
+release_version = 1.5.4
 ; DEBUG LEVEL: For production run set to 0, otherwise device will leak RAM while running!
 ; 0=None, 1=Error, 2=Warn, 3=Info, 4=Debug, 5=Verbose
 debug_level = 0
diff --git a/src/button.cpp b/src/button.cpp
index 3f75674a..4a816c14 100644
--- a/src/button.cpp
+++ b/src/button.cpp
@@ -6,7 +6,11 @@
 // Local logging tag
 static const char TAG[] = "main";
 
-void IRAM_ATTR ButtonIRQ() { ButtonPressedIRQ++; }
+void IRAM_ATTR ButtonIRQ() {
+  portENTER_CRITICAL(&timerMux);
+  ButtonPressedIRQ++;
+  portEXIT_CRITICAL(&timerMux);
+}
 
 void readButton() {
   if (ButtonPressedIRQ) {
diff --git a/src/ota.cpp b/src/ota.cpp
index c4f64c90..fdda780d 100644
--- a/src/ota.cpp
+++ b/src/ota.cpp
@@ -35,23 +35,9 @@ volatile bool isValidContentType = false;
 // Local logging tag
 static const char TAG[] = "main";
 
-void display(const uint8_t row, std::string status, std::string msg) {
-#ifdef HAS_DISPLAY
-  u8x8.setCursor(14, row);
-  u8x8.print((status.substr(0, 2)).c_str());
-  if (!msg.empty()) {
-    u8x8.clearLine(7);
-    u8x8.setCursor(0, 7);
-    u8x8.print(msg.substr(0, 16).c_str());
-  }
-#endif
-}
-
-// callback function to show download progress while streaming data
-void show_progress(size_t current, size_t size) {
-  char buf[17];
-  snprintf(buf, 17, "%-9lu (%3lu%%)",  current, current*100 / size);
-  display(4, "**", buf);
+// helper function to extract header value from header
+inline String getHeaderValue(String header, String headerName) {
+  return header.substring(strlen(headerName.c_str()));
 }
 
 void start_ota_update() {
@@ -99,7 +85,7 @@ void start_ota_update() {
   if (i >= 0) {
     ESP_LOGI(TAG, "Connected to %s", WIFI_SSID);
     display(1, "OK", "WiFi connected");
-    checkFirmwareUpdates(); // gets and flashes new firmware
+    do_ota_update(); // gets and flashes new firmware
   } else {
     ESP_LOGI(TAG, "Could not connect to %s, rebooting.", WIFI_SSID);
     display(1, " E", "no WiFi connect");
@@ -121,7 +107,10 @@ void start_ota_update() {
 
 } // start_ota_update
 
-void checkFirmwareUpdates() {
+
+void do_ota_update() {
+  char buf[17];
+
   // Fetch the latest firmware version
   ESP_LOGI(TAG, "Checking latest firmware version on server...");
   display(2, "**", "checking version");
@@ -140,24 +129,10 @@ void checkFirmwareUpdates() {
   }
   ESP_LOGI(TAG, "New firmware version v%s available. Downloading...",
            latest.c_str());
-  display(2, "OK", "");
-
-  processOTAUpdate(latest);
-}
-
-// helper function to extract header value from header
-inline String getHeaderValue(String header, String headerName) {
-  return header.substring(strlen(headerName.c_str()));
-}
-
-/**
- * OTA update processing
- */
-void processOTAUpdate(const String &version) {
-
-  char buf[17];
-  display(3, "**", "requesting file");
-  String firmwarePath = bintray.getBinaryPath(version);
+  display(2, "OK", latest.c_str());
+  
+  display(3, "**", "");
+  String firmwarePath = bintray.getBinaryPath(latest);
   if (!firmwarePath.endsWith(".bin")) {
     ESP_LOGI(TAG, "Unsupported binary format, OTA update cancelled.");
     display(3, " E", "file type error");
@@ -327,6 +302,25 @@ void processOTAUpdate(const String &version) {
   ESP_LOGI(TAG,
            "OTA update failed. Rebooting to runmode with current version.");
   client.stop();
+} // do_ota_update
+
+void display(const uint8_t row, std::string status, std::string msg) {
+#ifdef HAS_DISPLAY
+  u8x8.setCursor(14, row);
+  u8x8.print((status.substr(0, 2)).c_str());
+  if (!msg.empty()) {
+    u8x8.clearLine(7);
+    u8x8.setCursor(0, 7);
+    u8x8.print(msg.substr(0, 16).c_str());
+  }
+#endif
+}
+
+// callback function to show download progress while streaming data
+void show_progress(size_t current, size_t size) {
+  char buf[17];
+  snprintf(buf, 17, "%-9lu (%3lu%%)",  current, current*100 / size);
+  display(4, "**", buf);
 }
 
 // helper function to compare two versions. Returns 1 if v2 is
diff --git a/src/ota.h b/src/ota.h
index bda9fbe1..e426bb15 100644
--- a/src/ota.h
+++ b/src/ota.h
@@ -8,10 +8,10 @@
 #include <BintrayClient.h>
 #include <string>
 
-void checkFirmwareUpdates();
-void processOTAUpdate(const String &version);
+void do_ota_update();
 void start_ota_update();
 int version_compare(const String v1, const String v2);
 void show_progress(size_t current, size_t size);
+void display(const uint8_t row, std::string status, std::string msg);
 
 #endif // OTA_H