zero char is returned as space

Hi,
could you help me understand if this is an intended behaviour, or I'm
incorrectly querying a "char" field? I have simple table with column
declared as:
c_tinyint char NOT NULL

The column contains tiny integers in range 0-10. When I query the column
from my app using libpq values 1-10 are returned correctly as 0x1-0x10. But
value of zero is returned as 0x20 (expected 0x0).
The pgAdmin displays result of the query
SELECT c_tinyint, ascii(c_tinyint) FROM tbl
as shown below:
| c_tinyint | ascii |
| character(1) | integer |
| | 0 |
| | 1 |
| | 2 |
| | 3 |
| | 4 |

Thank you
K