diff --git a/configs/stm32f3discovery/include/board.h b/configs/stm32f3discovery/include/board.h
index b8f1555ec8..fb3406499e 100644
--- a/configs/stm32f3discovery/include/board.h
+++ b/configs/stm32f3discovery/include/board.h
@@ -100,17 +100,20 @@
 #define STM32_APB2_TIM1_CLKIN   (STM32_PCLK2_FREQUENCY)
 #define STM32_APB2_TIM8_CLKIN   (STM32_PCLK2_FREQUENCY)
 
+#define STM32_APB1_TIM15_CLKIN  (STM32_PCLK2_FREQUENCY)
+#define STM32_APB1_TIM16_CLKIN  (STM32_PCLK2_FREQUENCY)
+#define STM32_APB1_TIM17_CLKIN  (STM32_PCLK2_FREQUENCY)
+
 /* APB1 clock (PCLK1) is HCLK/2 (36MHz) */
 
 #define STM32_RCC_CFGR_PPRE1    RCC_CFGR_PPRE1_HCLKd2
 #define STM32_PCLK1_FREQUENCY   (STM32_HCLK_FREQUENCY/2)
 
-/* APB1 timers 2-4 will be twice PCLK1 (I presume the remaining will receive PCLK1) */
+/* APB1 timers 2-4 will be twice PCLK1 (REVISIT) */
 
 #define STM32_APB1_TIM2_CLKIN   (2*STM32_PCLK1_FREQUENCY)
 #define STM32_APB1_TIM3_CLKIN   (2*STM32_PCLK1_FREQUENCY)
 #define STM32_APB1_TIM4_CLKIN   (2*STM32_PCLK1_FREQUENCY)
-#define STM32_APB1_TIM5_CLKIN   (STM32_PCLK1_FREQUENCY)
 #define STM32_APB1_TIM6_CLKIN   (STM32_PCLK1_FREQUENCY)
 #define STM32_APB1_TIM7_CLKIN   (STM32_PCLK1_FREQUENCY)
 
diff --git a/configs/stm32f3discovery/nsh/defconfig b/configs/stm32f3discovery/nsh/defconfig
index 468e99f5cd..c487c0296a 100644
--- a/configs/stm32f3discovery/nsh/defconfig
+++ b/configs/stm32f3discovery/nsh/defconfig
@@ -235,7 +235,7 @@ CONFIG_ARCH_STACKDUMP=y
 # Board Settings
 #
 CONFIG_DRAM_START=0x20000000
-CONFIG_DRAM_SIZE=114688
+CONFIG_DRAM_SIZE=40960
 CONFIG_ARCH_HAVE_INTERRUPTSTACK=y
 CONFIG_ARCH_INTERRUPTSTACK=0
 
diff --git a/configs/stm32f3discovery/ostest/defconfig b/configs/stm32f3discovery/ostest/defconfig
index 4cfcc7c491..8dad4a846f 100644
--- a/configs/stm32f3discovery/ostest/defconfig
+++ b/configs/stm32f3discovery/ostest/defconfig
@@ -228,7 +228,7 @@ CONFIG_ARCH_STACKDUMP=y
 # Board Settings
 #
 CONFIG_DRAM_START=0x20000000
-CONFIG_DRAM_SIZE=114688
+CONFIG_DRAM_SIZE=40960
 CONFIG_ARCH_HAVE_INTERRUPTSTACK=y
 CONFIG_ARCH_INTERRUPTSTACK=0
 
diff --git a/configs/stm32f3discovery/usbnsh/defconfig b/configs/stm32f3discovery/usbnsh/defconfig
index d1f549536c..9755498151 100644
--- a/configs/stm32f3discovery/usbnsh/defconfig
+++ b/configs/stm32f3discovery/usbnsh/defconfig
@@ -235,7 +235,7 @@ CONFIG_ARCH_STACKDUMP=y
 # Board Settings
 #
 CONFIG_DRAM_START=0x20000000
-CONFIG_DRAM_SIZE=114688
+CONFIG_DRAM_SIZE=40960
 CONFIG_ARCH_HAVE_INTERRUPTSTACK=y
 CONFIG_ARCH_INTERRUPTSTACK=0