Problem with nested UPDATE queries

Question

I cannot make an update query work. As a first step, the following one works correctly:

UPDATE Tab1  
SET Tab1.a = '3'
WHERE
    Tab1.id IN ( 123, 456 );

where id is the primary key of Tab1.
However when I add a select to get the set of values Tab1.id must be in, I get the following MySQL error:

Error code: 1093
You can't specify target table 'Tab1' for update in FROM clause.

This is the complete query:

UPDATE Tab1  
    SET Tab1.a = '3'
    WHERE
        Tab1.id IN ( 
            SELECT Tab1.id 
            FROM Tab1, Tab2 
            WHERE Tab1.b = Tab2.b AND Tab1.c = '4'
        );

I cannot see how to fix this error.
Am I forced to split this query in two?

Thank you!