[Context] In software development, the quality attributes that systems should exhibit are often expressed as non-functional requirements (NFRs). However, unlike functional requirements, there is no widely adopted writing format for NFRs. [Problem] This deficiency, and the more complex nature of NFRs due to their difficult quantification and architectural level of abstraction, poses obstacles for the specification of NFRs in practice. [Results] Following the design cycle methodology, we put forward a process for developing an NFR template based on meta-requirements from literature and gathered from practitioners in a focus group, and two existing templates. We validated the template through interviews with target users from three organizations, focusing on whether it could help practitioners overcome specific challenges in NFR writing. [Contribution] The interviewees appreciated the explicit documentation of measurable fit criteria the most, as it allows users to make the NFR quantifiable, and found the template easy to use. All expressed an intention to use the template again in the future.