Tinyint Overflow Error

I encounter the following error :

Server: Msg 8115, Level 16, State 2, Procedure kssp_UpdateLeague, Line 107
Arithmetic overflow error converting expression to data type tinyint.

When I hit the following code:

SET @A = @B - @C

-------------------------------------------

@A is defined as :
DECLARE @A INT

@B and @C are populated in a fetch :
FETCH NEXT FROM FixtureList INTO @B, @C

and FixtureList is defined as :

DECLARE FixtureList CURSOR FOR
SELECT HomeScore, AwayScore FROM fixtures
WHERE homescore IS NOT NULL AND awayscore IS NOT NULL

The fields HomeScore and AwayScore are defined as Tinyint

@B and @C are typically between 0 and 10. I reckon the problem may be with the precision of the data types but I don't know how to prove this or how to fix. I've tried various combinations of convert and cast at various points in the expression (SET @A = @B - @C) but to no avail.

Interestingly (or not) if I run the following select I get the same error :

SELECT DATE01, HOMESCORE, AWAYSCORE, HOMESCORE - AWAYSCORE FROM fixtures