A union is urging backstage theatre workers to check their contracts for clauses that prevent them talking about their rates of pay.
Bectu said many backstage theatre contracts include such clauses, which aim to keep terms and wages confidential.
The union believes the clauses should not be included and may be used to hide unfair pay practices.
It said The Equality Act 2010, and in particular Section 77, protects "the right that employees can legally discuss their work pay with colleagues".
The legislation states that employers "should not discipline anyone for discussing their work pay" and "should not include clauses in employee contracts that prevent workers from talking about pay".
The union stressed that the law only protects employees when discussing pay for the purpose of establishing an unfair pay issue in a workplace.
Bectu Assistant National Secretary Helen Ryan said: “It’s no secret that low pay is one of the core issues driving the chronic skills shortage in the UK theatre sector.
"We want to help implement pay consistency across the industry so it’s imperative that workers aren’t wrongfully bound by clauses that prevent them from discussing their pay, or allow for disciplinary action for doing so."
She added: “Productions we have spoken to about this have overwhelmingly responded positively and removed the clause, which we hope will encourage people to call out these clauses when they see them."