diff --git a/os/hal/platforms/SPC563Mxx/hal_lld.c b/os/hal/platforms/SPC563Mxx/hal_lld.c
index a140536e3..921fc744f 100644
--- a/os/hal/platforms/SPC563Mxx/hal_lld.c
+++ b/os/hal/platforms/SPC563Mxx/hal_lld.c
@@ -112,7 +112,7 @@ void spc_clock_init(void) {
 
 #if !SPC5_NO_INIT
   /* PLL activation.*/
-  FMPLL.ESYNCR1.B.EMODE     = 1;
+  FMPLL.ESYNCR1.B.EMODE     = 1;                    /* Enhanced mode on.    */
   FMPLL.ESYNCR1.B.CLKCFG   &= 1;                    /* Bypass mode, PLL off.*/
   FMPLL.ESYNCR1.B.CLKCFG   |= 2;                    /* PLL on.              */
   FMPLL.ESYNCR1.B.EPREDIV   = SPC5_CLK_PREDIV;
diff --git a/os/hal/platforms/SPC563Mxx/hal_lld.h b/os/hal/platforms/SPC563Mxx/hal_lld.h
index 5e8296a22..0cec2b0ac 100644
--- a/os/hal/platforms/SPC563Mxx/hal_lld.h
+++ b/os/hal/platforms/SPC563Mxx/hal_lld.h
@@ -15,6 +15,10 @@
 /**
  * @file    SPC563Mxx/hal_lld.h
  * @brief   SPC563Mxx HAL subsystem low level driver header.
+ * @pre     This module requires the following macros to be defined in the
+ *          @p board.h file:
+ *          - SPC5_XOSC_CLK.
+ *          .
  *
  * @addtogroup HAL
  * @{