How to Fine-Tune Safely on a Budget: Model Adaptation Using Minimal Resources

Anh C. Pham, Mihir Thalanki, Michael Sun, Aditya Chaloo, Ankita Gupta, Tian Xia, Aditya Mate, Ehi Nosakhare, Soundararajan Srinivasan


Abstract
Supervised fine-tuning (SFT) on benign data can paradoxically erode a language model’s safety alignment, a phenomenon known as catastrophic forgetting of safety behaviors. Although prior work shows that randomly adding safety examples can reduce harmful output, the principles that make certain examples more effective than others remain poorly understood. This paper investigates the hypothesis that the effectiveness of a safety example is governed by two key factors: its instruction-response behavior (e.g., refusal vs. explanation) and its semantic diversity across harm categories. We systematically evaluate sampling strategies based on these axes and find that structured, diversity-aware sampling significantly improves model safety. Our method reduces harmfulness by up to 41% while adding only 0.05% more data to the fine-tuning set.
Anthology ID:
2025.emnlp-industry.138
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
November
Year:
2025
Address:
Suzhou (China)
Editors:
Saloni Potdar, Lina Rojas-Barahona, Sebastien Montella
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1970–1981
Language:
URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-industry.138/
DOI:
Bibkey:
Cite (ACL):
Anh C. Pham, Mihir Thalanki, Michael Sun, Aditya Chaloo, Ankita Gupta, Tian Xia, Aditya Mate, Ehi Nosakhare, and Soundararajan Srinivasan. 2025. How to Fine-Tune Safely on a Budget: Model Adaptation Using Minimal Resources. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 1970–1981, Suzhou (China). Association for Computational Linguistics.
Cite (Informal):
How to Fine-Tune Safely on a Budget: Model Adaptation Using Minimal Resources (Pham et al., EMNLP 2025)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-industry.138.pdf