diff --git a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_MICRO/startup_stm32f10x_md.s b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_MICRO/startup_stm32f10x_md.s
index 3f86c837d9..29bfe7a7c3 100644
--- a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_MICRO/startup_stm32f10x_md.s
+++ b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_MICRO/startup_stm32f10x_md.s
@@ -37,7 +37,7 @@ Stack_Size      EQU     0x00000400
 
 Stack_Mem       SPACE   Stack_Size
 
-__initial_sp    EQU     0x20000000 ; Top of RAM
+__initial_sp    EQU     0x20005000 ; Top of RAM
 
 
 ; <h> Heap Configuration
diff --git a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_STD/startup_stm32f10x_md.s b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_STD/startup_stm32f10x_md.s
index 74da96cd7a..370b21864d 100644
--- a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_STD/startup_stm32f10x_md.s
+++ b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F103RB/TOOLCHAIN_ARM_STD/startup_stm32f10x_md.s
@@ -34,7 +34,7 @@ Stack_Size      EQU     0x00000400
 
                 AREA    STACK, NOINIT, READWRITE, ALIGN=3
 Stack_Mem       SPACE   Stack_Size
-__initial_sp
+__initial_sp    EQU     0x20005000
 
 
 ; <h> Heap Configuration