diff --git a/embed/trezorhal/secbool.h b/embed/trezorhal/secbool.h
index cfb6086f7..78e1cbfd6 100644
--- a/embed/trezorhal/secbool.h
+++ b/embed/trezorhal/secbool.h
@@ -4,7 +4,7 @@
 #include <stdint.h>
 
 typedef uint32_t secbool;
-#define sectrue  0xAAAAAAAA
-#define secfalse 0x00000000
+#define sectrue  0xAAAAAAAAU
+#define secfalse 0x00000000U
 
 #endif