Nicholas Perrin in his 2002 monograph, Thomas and Tatian: The Relationship between the Gospel of Thomas and the Diatessaron, and in a series of subsequent publications has proposed that, if one translates it back into Syriac, a series of 502 catchwords can be found to run through the Gospel of Thomas. According to Perrin this number is greater than the number of catchwords in Coptic (269) or in Greek (263) and demonstrates that the Gospel of Thomas was originally composed in Syriac, which in turn makes it likely that the Gospel of Thomas was written with a knowledge of Tatian's Diatessaron. Here, a sample of Perrin's alleged catchwords is investigated and is found implausible. Consequently his late dating of the Gospel of Thomas cannot be established. Nicholas Perrin in his 2002 monograph, Thomas and Tatian: The Relationship between the Gospel of Thomas and the Diatessaron, and in a series of subsequent publications has proposed that, if one translates it back into Syriac, a series of 502 catchwords can be found to run through the Gospel of Thomas. According to Perrin this number is greater than the number of catchwords in Coptic (269) or in Greek (263) and demonstrates that the Gospel of Thomas was originally composed in Syriac, which in turn makes it likely that the Gospel of Thomas was written with a knowledge of Tatian's Diatessaron. Here, a sample of Perrin's alleged catchwords is investigated and is found implausible. Consequently his late dating of the Gospel of Thomas cannot be established.