diff --git a/firmware/target/arm/usb-fw-pp502x.c b/firmware/target/arm/usb-fw-pp502x.c
index cfb284a77c..b4c262757d 100644
--- a/firmware/target/arm/usb-fw-pp502x.c
+++ b/firmware/target/arm/usb-fw-pp502x.c
@@ -26,6 +26,7 @@
 #include "usb.h"
 #include "button.h"
 #include "ata.h"
+#include "string.h"
 #include "arcotg_udc.h"
 
 #ifdef HAVE_USBSTACK