diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3ab8c9cf3980..4da1e7aaf9d5 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -777,11 +777,19 @@ char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
 	if (spec.field_width > 0)
 		len = min_t(int, spec.field_width, 64);
 
-	for (i = 0; i < len && buf < end - 1; i++) {
-		buf = hex_byte_pack(buf, addr[i]);
+	for (i = 0; i < len; ++i) {
+		if (buf < end)
+			*buf = hex_asc_hi(addr[i]);
+		++buf;
+		if (buf < end)
+			*buf = hex_asc_lo(addr[i]);
+		++buf;
 
-		if (buf < end && separator && i != len - 1)
-			*buf++ = separator;
+		if (separator && i != len - 1) {
+			if (buf < end)
+				*buf = separator;
+			++buf;
+		}
 	}
 
 	return buf;