diff --git a/os/hal/platforms/STM32F2xx/hal_lld.h b/os/hal/platforms/STM32F2xx/hal_lld.h
index 64f68b792..5984cf3a5 100644
--- a/os/hal/platforms/STM32F2xx/hal_lld.h
+++ b/os/hal/platforms/STM32F2xx/hal_lld.h
@@ -874,7 +874,7 @@
 #else /* !STM32_LSI_ENABLED */
 
 #if STM32_RTCSEL == STM32_RTCSEL_LSI
-#error "required LSI clock is not enabled"
+#error "LSI not enabled, required by STM32_RTCSEL"
 #endif
 
 #endif /* !STM32_LSI_ENABLED */
diff --git a/os/hal/platforms/STM32F4xx/hal_lld.h b/os/hal/platforms/STM32F4xx/hal_lld.h
index b55a68a4e..71b0c503b 100644
--- a/os/hal/platforms/STM32F4xx/hal_lld.h
+++ b/os/hal/platforms/STM32F4xx/hal_lld.h
@@ -894,7 +894,7 @@
 #else /* !STM32_LSI_ENABLED */
 
 #if STM32_RTCSEL == STM32_RTCSEL_LSI
-#error "required LSI clock is not enabled"
+#error "LSI not enabled, required by STM32_RTCSEL"
 #endif
 
 #endif /* !STM32_LSI_ENABLED */