diff --git a/irr_main.c b/irr_main.c
index df1a7e0..b1379ad 100644
--- a/irr_main.c
+++ b/irr_main.c
@@ -159,7 +159,7 @@ analog_seed_rng(void)
 static inline uint32_t
 letoh_32(uint8_t *v)
 {
-	return v[0] | (v[1] << 8) | (v[2] << 16) | (v[3] << 24);
+	return v[0] | (v[1] << 8) | (v[2] << 16) | ((unsigned)v[3] << 24);
 }
 
 struct chaninfo {