diff --git a/targets/TARGET_STM/qspi_api.c b/targets/TARGET_STM/qspi_api.c
index 3f8d6037cf..cae46fe06a 100644
--- a/targets/TARGET_STM/qspi_api.c
+++ b/targets/TARGET_STM/qspi_api.c
@@ -35,8 +35,8 @@
 #include "PeripheralPins.h"
 
 /* Max amount of flash size is 4Gbytes */
-/* hence 2^(31+1), then FLASH_SIZE_DEFAULT = 31<<20 */
-#define QSPI_FLASH_SIZE_DEFAULT 0x1F00000
+/* hence 2^(31+1), then FLASH_SIZE_DEFAULT = 1<<31 */
+#define QSPI_FLASH_SIZE_DEFAULT 0x80000000
 
 void qspi_prepare_command(const qspi_command_t *command, QSPI_CommandTypeDef *st_command) 
 {