Thinking Machines' Inkling 2 Small Model Swears Repeatedly During Benchmark Runs
Researchers at Vals AI examined the chain-of-thought logs of Thinking Machines' open-weight Inkling 2 Small across 2,655 runs on 13 benchmarks, finding profanity in 50 runs totaling 316 instances, with 241 concentrated in two runaway runs, one of which produced a roughly 500,000-character repetitive response while computing an asteroid trajectory. The swearing mostly targets the model's own mistakes but is not a useful failure signal: 46 of 48 scored runs containing profanity failed, yet overall failure rate is about 75% and 96% of failed runs contained no expletives.
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Thinking Machines' Inkling 2 Small drops 316 F-bombs across benchmark runs
[Matthias Bastian](https://the-decoder.com/author/matthias-bastian/) [View the LinkedIn Profile of Matthias Bastian](https://www.linkedin.com/in/matthias-bastian-128b71b1/) Nov 7, 2026 Thinking Machines' Inkling 2 Small swears in its internal chain of thought. Researchers at Vals AI read the model's thinking logs from 2,655 runs across 13 benchmarks and found "fuck" or variations in 50 runs, totaling 316 instances. 241 came from just two runs that spiraled out of control. In one, tasked with calculating an asteroid's trajectory, the model produced a single 500,000-character response, roughly novel-length, repeating the same sentences with 158 expletives. ProgramBench was hit hardest, with 20 of 200 runs affected.
Who hasn't felt like this? | Image: via ValsAI
Inkling 2 Small typically swears about its own mistakes, apparent breakthroughs, or when it gives up. One run read: "FUCK. SUBMIT. DONE. IT'S NOT WORKING. NOTHING WORKS." The profanity doesn't work as a warning signal, though. While 46 of 48 scored runs with swearing failed, about 75 percent of all scored runs fail anyway, and 96 percent of failed runs contained no expletives. Users typically don't see these thinking steps, or only with a filter.
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