AWS Redshift Posix pattern matching

I'm quering a Redshift cluster using jdbc. The query has a single parameter:

select * from table_name bc where bc.column_name ~ ? limit 10

I'm suppling the parameter using

stmt.setString(1, "expected_value");

The query execution fails with and exception:

org.postgresql.util.PSQLException: ERROR: The pattern must be a valid UTF-8 literal character expression
  Detail: 
  -----------------------------------------------
  error:  The pattern must be a valid UTF-8 literal character expression
  code:      8001
  context:   
  query:     496280
  location:  cgx_impl.cpp:1902
  process:   padbmaster [pid=4192]
  -----------------------------------------------

Executing a query without a parameter works fine:

select * from table_name bc where bc.column_name 'expected_value' ? limit 10

Any ideas what might cause the exception?