diff --git a/src/lib/OPTIONS/options.cpp b/src/lib/OPTIONS/options.cpp
index 20c50f90f6..645d47a4b9 100644
--- a/src/lib/OPTIONS/options.cpp
+++ b/src/lib/OPTIONS/options.cpp
@@ -26,7 +26,6 @@ const char *wifi_ap_address = "10.0.0.1";
 
 // Discriminator value used to determine if the device has been reflashed and therefore
 // the SPIFSS settings are obsolete and the flashed settings should be used in preference
-// If STM32, this contains part of the flashed UID used to determine if bind phrase flashed
 uint32_t flash_discriminator;
 
 #if !defined(TARGET_UNIFIED_TX) && !defined(TARGET_UNIFIED_RX)
@@ -167,8 +166,11 @@ firmware_options_t firmwareOptions;
 bool options_init()
 {
     firmwareOptions = flashedOptions;
-    // Use the last 4 digits of the UID as the flash discriminator
-    flash_discriminator = flashedOptions.uid[2] << 24 | flashedOptions.uid[3] << 16 | flashedOptions.uid[4] << 8 | flashedOptions.uid[5];
+#if defined(TARGET_STM32) && defined(FLASH_DISCRIM)
+    // This is defined by the build_flags.py and used by STM32 (ESP gets it from json)
+    // It is always defined even though intellisense doesn't pick it up
+    flash_discriminator = FLASH_DISCRIM;
+#endif
     return true;
 }
 
diff --git a/src/python/build_flags.py b/src/python/build_flags.py
index 44f9c591a6..4ba7d1577b 100644
--- a/src/python/build_flags.py
+++ b/src/python/build_flags.py
@@ -136,16 +136,17 @@ def get_git_sha():
 def get_version():
     return string_to_ascii(env.get('GIT_VERSION'))
 
+json_flags['flash-discriminator'] = randint(1,2**32-1)
+
 process_flags("user_defines.txt")
 process_flags("super_defines.txt") # allow secret super_defines to override user_defines
 version_to_env()
 build_flags.append("-DLATEST_COMMIT=" + get_git_sha())
 build_flags.append("-DLATEST_VERSION=" + get_version())
 build_flags.append("-DTARGET_NAME=" + re.sub("_VIA_.*", "", target_name))
+build_flags.append("-DFLASH_DISCRIM=" + str(json_flags['flash-discriminator']))
 condense_flags()
 
-json_flags['flash-discriminator'] = randint(1,2**32-1)
-
 if '-DRADIO_SX127X=1' in build_flags:
     # disallow setting 2400s for 900
     if fnmatch.filter(build_flags, '*-DRegulatory_Domain_ISM_2400') or \