diff --git a/variants/Generic_F401Cx/variant.h b/variants/Generic_F401Cx/variant.h
index 819133bb62..c39bbc51a6 100644
--- a/variants/Generic_F401Cx/variant.h
+++ b/variants/Generic_F401Cx/variant.h
@@ -110,8 +110,10 @@ extern "C" {
 #define PIN_SERIAL_TX           PA9
 
 #ifdef ARDUINO_BLACKPILL_F401CC
+#ifndef HSE_VALUE
 #define HSE_VALUE               25000000U
 #endif
+#endif
 
 #ifdef __cplusplus
 } // extern "C"
diff --git a/variants/Generic_F411Cx/variant.h b/variants/Generic_F411Cx/variant.h
index c4488de4b3..d134651319 100644
--- a/variants/Generic_F411Cx/variant.h
+++ b/variants/Generic_F411Cx/variant.h
@@ -113,8 +113,10 @@ extern "C" {
 #define PIN_SERIAL_TX           PA9
 
 #ifdef ARDUINO_BLACKPILL_F411CE
+#ifndef HSE_VALUE
 #define HSE_VALUE               25000000U
 #endif
+#endif
 
 #ifdef __cplusplus
 } // extern "C"