fetching timy values above 127 returns. MYSQL_DATA_TRUNCATED

mysql_stmt_fetch() returns MYSQL_DATA_TRUNCATED when fetching TINYINT UNSiGNED from DB with values above 127. Fetched values seem nevertheless to be correct in range 0 to 255.

Consecutive fetches return return-code of 1st fetch, regardless of read value.
Latter observation not verified.

attached test produces:
for i in 1 2 3 4 9 ; do ./a.out $i ; done
id 1: tiny 127
id 2: data truncated --> id 2: tiny 128
id 3: tiny 32
id 4: data truncated --> id 4: tiny 192
id 9: no data --> id 9: tiny 0