diff --git a/core/embed/sys/startup/inc/sys/bootutils.h b/core/embed/sys/startup/inc/sys/bootutils.h
index 10b069e913..25cde30bae 100644
--- a/core/embed/sys/startup/inc/sys/bootutils.h
+++ b/core/embed/sys/startup/inc/sys/bootutils.h
@@ -45,13 +45,6 @@ void __attribute__((noreturn)) reboot_and_upgrade(const uint8_t hash[32]);
 // unrecoverable error state.
 void __attribute__((noreturn)) secure_shutdown(void);
 
-// Alternative memset with slightly different arguments
-//
-// This function writes a 32-bit value to a range of memory addresses.
-// The range is defined by the start and stop pointers and must
-// be aligned to 4 bytes.
-void memset_reg(volatile void *start, volatile void *stop, uint32_t val);
-
 // Jumps to the next booting stage (e.g. bootloader to firmware).
 // `address` points to the flash at the vector table of the next stage.
 //
diff --git a/core/embed/sys/startup/stm32f4/startup_init.c b/core/embed/sys/startup/stm32f4/startup_init.c
index 52634a030f..f934632149 100644
--- a/core/embed/sys/startup/stm32f4/startup_init.c
+++ b/core/embed/sys/startup/stm32f4/startup_init.c
@@ -240,10 +240,11 @@ __attribute((used)) void clear_otg_hs_memory(void) {
   __HAL_RCC_USB_OTG_HS_CLK_ENABLE();  // enable USB_OTG_HS peripheral clock so
                                       // that the peripheral memory is
                                       // accessible
-  memset_reg(
-      (volatile void *)USB_OTG_HS_DATA_FIFO_RAM,
-      (volatile void *)(USB_OTG_HS_DATA_FIFO_RAM + USB_OTG_HS_DATA_FIFO_SIZE),
-      0);
+  __IO uint32_t* usb_fifo_ram = (__IO uint32_t*)USB_OTG_HS_DATA_FIFO_RAM;
+
+  for (uint32_t i = 0; i < USB_OTG_HS_DATA_FIFO_SIZE / 4; i++) {
+    usb_fifo_ram[i] = 0;
+  }
 
   __HAL_RCC_USB_OTG_HS_CLK_DISABLE();  // disable USB OTG_HS peripheral clock as
                                        // the peripheral is not needed right now