diff --git a/DCCTimerESP.cpp b/DCCTimerESP.cpp
index 93711aa..e57f6af 100644
--- a/DCCTimerESP.cpp
+++ b/DCCTimerESP.cpp
@@ -76,8 +76,13 @@ int DCCTimer::freeMemory() {
 #endif
 
 ////////////////////////////////////////////////////////////////////////
-
 #ifdef ARDUINO_ARCH_ESP32
+
+#include "esp_idf_version.h"
+#if ESP_IDF_VERSION_MAJOR > 4
+#error "DCC-EX does not support compiling with IDF version 5.0 or later. Downgrade your ESP32 library to a version that contains IDE version 4. Arduino ESP32 library 3.0.0 is too new. Downgrade to one of 2.0.9 to 2.0.17"
+#endif
+
 #include "DIAG.h"
 #include <driver/adc.h>
 #include <soc/sens_reg.h>
diff --git a/GITHUB_SHA.h b/GITHUB_SHA.h
index 4807e45..6abb9b3 100644
--- a/GITHUB_SHA.h
+++ b/GITHUB_SHA.h
@@ -1 +1 @@
-#define GITHUB_SHA "devel-202405232026Z"
+#define GITHUB_SHA "devel-202406021945Z"
diff --git a/platformio.ini b/platformio.ini
index a03ff61..b39b136 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -164,7 +164,11 @@ monitor_echo = yes
 build_flags = -mcall-prologues
 
 [env:ESP32]
-platform = espressif32
+; Lock version to 6.7.0 as that is
+; Arduino v2.0.16 (based on IDF v4.4.7)
+; which is the latest version based
+; on IDF v4. We can not use IDF v5.
+platform = espressif32 @ 6.7.0
 board = esp32dev
 framework = arduino
 lib_deps = ${env.lib_deps}