diff --git a/os/hal/platforms/STM32F1xx/hal_lld.c b/os/hal/platforms/STM32F1xx/hal_lld.c
index ad13c21f8..eb87a1a84 100644
--- a/os/hal/platforms/STM32F1xx/hal_lld.c
+++ b/os/hal/platforms/STM32F1xx/hal_lld.c
@@ -204,6 +204,10 @@ void stm32_clock_init(void) {
   while ((RCC->CFGR & RCC_CFGR_SWS) != (STM32_SW << 2))
     ;                                       /* Waits selection complete.    */
 #endif
+
+#if !STM32_HSI_ENABLED
+  RCC->CR &= ~RCC_CR_HSION;
+#endif
 #endif /* !STM32_NO_INIT */
 }
 
@@ -285,6 +289,10 @@ void stm32_clock_init(void) {
   while ((RCC->CFGR & RCC_CFGR_SWS) != (STM32_SW << 2))
     ;
 #endif
+
+#if !STM32_HSI_ENABLED
+  RCC->CR &= ~RCC_CR_HSION;
+#endif
 #endif /* !STM32_NO_INIT */
 }
 #else
diff --git a/readme.txt b/readme.txt
index 626419d25..6ee12707e 100644
--- a/readme.txt
+++ b/readme.txt
@@ -89,6 +89,7 @@
 *****************************************************************************
 
 *** 2.5.2 ***
+- FIX: Fixed STM32F103 HSI configuration (bug #399).
 - FIX: Fixed patch to allow simulator to be restarted quicker (bug #398).
 - FIX: Fixed blkDisconnect macro typo (bug #397).
 - FIX: Fixed STM32 SPI (V2) driver hangs (bug 3608241).