Knowledge leakage is a key risk for start-ups particularly when that knowledge relates to the firm’s innovation and is therefore competitively sensitive. Leakage of competitively sensitive knowledge can lead to financial losses and erosion of competitive advantage. Start-ups are particularly vulnerable to knowledge leakage compared to mature enterprises since they have limited resources to devote to protective measures, rely on relatively fewer product/innovation lines to sustain business success, and experience greater organizational change making it difficult to control the complex and evolving security risk landscape. Current research on (knowledge) leakage mitigation methods don’t adequately address the needs of start-ups. This paper sets out to address the gaps in current research relating to leakage mitigation particularly focusing on IP protection in start-ups. We propose a new knowledge-leakage mitigation framework, the Risk Window, as a precursor to a process model designed to assist start-ups to secure their competitively sensitive knowledge.