diff --git a/demos/ARMCM3-STM32F103-FATFS-GCC/mcuconf.h b/demos/ARMCM3-STM32F103-FATFS-GCC/mcuconf.h
index e6216b886..13e210f5a 100644
--- a/demos/ARMCM3-STM32F103-FATFS-GCC/mcuconf.h
+++ b/demos/ARMCM3-STM32F103-FATFS-GCC/mcuconf.h
@@ -34,6 +34,11 @@
  * 0...3        Lowest...Highest.
  */
 
+/*
+ * HAL driver settings.
+ */
+#define STM32_SYSCLK                72
+
 /*
  * ADC driver system settings.
  */
diff --git a/demos/ARMCM3-STM32F103-GCC/mcuconf.h b/demos/ARMCM3-STM32F103-GCC/mcuconf.h
index e6216b886..13e210f5a 100644
--- a/demos/ARMCM3-STM32F103-GCC/mcuconf.h
+++ b/demos/ARMCM3-STM32F103-GCC/mcuconf.h
@@ -34,6 +34,11 @@
  * 0...3        Lowest...Highest.
  */
 
+/*
+ * HAL driver settings.
+ */
+#define STM32_SYSCLK                72
+
 /*
  * ADC driver system settings.
  */