diff --git a/Source/portable/GCC/STR75x/port.c b/Source/portable/GCC/STR75x/port.c
index 3050a6221..2cce4c643 100644
--- a/Source/portable/GCC/STR75x/port.c
+++ b/Source/portable/GCC/STR75x/port.c
@@ -192,7 +192,7 @@ TB_InitTypeDef      TB_InitStructure;
 	/* Setup the TB for the generation of the tick interrupt. */
 	TB_InitStructure.TB_Mode = TB_Mode_Timing;
 	TB_InitStructure.TB_CounterMode = TB_CounterMode_Down;
-	TB_InitStructure.TB_Prescaler = portPRESCALE;
+	TB_InitStructure.TB_Prescaler = portPRESCALE - 1;
 	TB_InitStructure.TB_AutoReload = ( ( configCPU_CLOCK_HZ / ( portPRESCALE + 1 ) ) / configTICK_RATE_HZ ) + 1;
 	TB_Init(&TB_InitStructure);
 	
diff --git a/Source/portable/IAR/STR75x/port.c b/Source/portable/IAR/STR75x/port.c
index d6e3a339b..588508e01 100644
--- a/Source/portable/IAR/STR75x/port.c
+++ b/Source/portable/IAR/STR75x/port.c
@@ -207,7 +207,7 @@ TB_InitTypeDef      TB_InitStructure;
 	/* Setup the TB for the generation of the tick interrupt. */
 	TB_InitStructure.TB_Mode = TB_Mode_Timing;
 	TB_InitStructure.TB_CounterMode = TB_CounterMode_Down;
-	TB_InitStructure.TB_Prescaler = portPRESCALE;
+	TB_InitStructure.TB_Prescaler = portPRESCALE - 1;
 	TB_InitStructure.TB_AutoReload = ( ( configCPU_CLOCK_HZ / ( portPRESCALE + 1 ) ) / configTICK_RATE_HZ ) + 1;
 	TB_Init(&TB_InitStructure);