diff --git a/arch/arm/src/sama5/sam_lowputc.c b/arch/arm/src/sama5/sam_lowputc.c
index 6931c6ceed0..2685335ca25 100644
--- a/arch/arm/src/sama5/sam_lowputc.c
+++ b/arch/arm/src/sama5/sam_lowputc.c
@@ -149,10 +149,10 @@
 #  undef HAVE_UART_CONSOLE
 #endif
 
-/* The UART/USART modules are driven by the main clock (MCK). */
+/* The UART/USART modules are driven by the peripheral clock (MCK or MCK2). */
 
-#define SAM_USART_CLOCK  BOARD_MCK_FREQUENCY  /* Frequency of the main clock */
-#define SAM_MR_USCLKS    UART_MR_USCLKS_MCK   /* Source = Main clock */
+#define SAM_USART_CLOCK  BOARD_USART_FREQUENCY /* Frequency of the USART clock */
+#define SAM_MR_USCLKS    UART_MR_USCLKS_MCK    /* Source = Main clock */
 
 /* Select USART parameters for the selected console */
 
diff --git a/arch/arm/src/sama5/sam_serial.c b/arch/arm/src/sama5/sam_serial.c
index 8dcc05bdb26..479caf5b0c3 100644
--- a/arch/arm/src/sama5/sam_serial.c
+++ b/arch/arm/src/sama5/sam_serial.c
@@ -382,10 +382,10 @@
 #  define USART4_ASSIGNED      1
 #endif
 
-/* The UART/USART modules are driven by the main clock (MCK). */
+/* The UART/USART modules are driven by the peripheral clock (MCK or MCK2). */
 
-#define SAM_USART_CLOCK  BOARD_MCK_FREQUENCY  /* Frequency of the main clock */
-#define SAM_MR_USCLKS    UART_MR_USCLKS_MCK   /* Source = Main clock */
+#define SAM_USART_CLOCK  BOARD_USART_FREQUENCY /* Frequency of the USART clock */
+#define SAM_MR_USCLKS    UART_MR_USCLKS_MCK    /* Source = Main clock */
 
 /****************************************************************************
  * Private Types