diff --git a/t/t_util.c b/t/t_util.c
index 1e54d1f..6e92b04 100644
--- a/t/t_util.c
+++ b/t/t_util.c
@@ -104,15 +104,15 @@ t_compare_num(ull, unsigned long long, "llu");
 t_compare_num(sz, size_t, "zu");
 t_compare_num(i8, int8_t, PRId8);
 t_compare_num(u8, uint8_t, PRIu8);
-t_compare_num(x8, uint8_t, PRIx8);
+t_compare_num(x8, uint8_t, "#" PRIx8);
 t_compare_num(i16, int16_t, PRId16);
 t_compare_num(u16, uint16_t, PRIu16);
-t_compare_num(x16, uint16_t, PRIx16);
+t_compare_num(x16, uint16_t, "#" PRIx16);
 t_compare_num(i32, int32_t, PRId32);
 t_compare_num(u32, uint32_t, PRIu32);
-t_compare_num(x32, uint32_t, PRIx32);
+t_compare_num(x32, uint32_t, "#" PRIx32);
 t_compare_num(i64, int64_t, PRId64);
 t_compare_num(u64, uint64_t, PRIu64);
-t_compare_num(x64, uint64_t, PRIx64);
+t_compare_num(x64, uint64_t, "#" PRIx64);
 
 #undef t_compare_num