diff --git a/src/yyjson.c b/src/yyjson.c
index e199a73..3a99d5c 100644
--- a/src/yyjson.c
+++ b/src/yyjson.c
@@ -7258,7 +7258,7 @@ static_inline u8 *write_u32_len_1_to_9(u32 val, u8 *buf) {
     if (val >= 100000000) {
         u32 hi = val / 10000000;
         val = val - hi * 10000000;
-        *buf++ = (u8)hi + (u8)'0';
+        *buf++ = (u8)(hi + '0');
     }
     return write_u32_len_1_to_8((u32)val, buf);
 }