In all domains of life, three stop codons are thought to terminate translation: TAG (known as amber), TGA (known as opal) and TAA (known as ochre). Ivanova et al. analysed a global collection of 1,776 samples from the Integrated Microbial Genomes database (which includes both environmental and human-associated samples) and found extensive stop codon reassignment. Interestingly, bacteria only reassigned opal, eukaryotes only reassigned ochre, viruses reassigned amber and opal,and no reassignments were found in archaea. In the human microbiome samples, the authors also identified several DNA phages that have amber reassignments. As bacteria do not reassign amber, this questions the dogma that genetic code differences between phages and their bacterial hosts are a barrier to phage infection. Accordingly, the genomes of amber-recoded phages contain genes for peptide chain release factor 2 — which terminates translation at ochre and opal codons — as well as a non-canonical Gln-tRNACUA — which reassigns amber to glutamine. This suggests that phages can actively interfere with translation of opal-recoded host genes and use their own, amber-recoded alternative genetic code.