This study investigates the influence of the bore-to-nominal diameter ratio ($d_0/D_0$) on hydrogen embrittlement in a martensitic stainless-steel alloy through tensile testing of hollow specimens. Various geometries were tested, including one designed according to ISO 7039:2024 standard. A conventional test at ambient pressure in air was used as a baseline for comparison. The primary aim was to assess how different $d_0/D_0$-ratios affect the mechanical properties and susceptibility to hydrogen embrittlement. In order to check the quality of the bore hole of the tensile tests, surface roughness measurements were conducted, as surface irregularities can significantly impact hydrogen-induced cracking.The results indicate a strong correlation between the $d_0/D_0$ -ratio and the onset of hydrogen-induced fracture. Hollow specimens with higher $d_0/D_0$-ratios depicted premature failure compared to those with lower ratios. A comparison of fracture behavior between solid and hollow specimens, tested in inert and ambient atmospheres, highlighted significant differences in the fracture mechanisms. Notably, the yielding strengths and ultimate tensile strength remained comparable and independent of the $d_0/D_0$-ratio and environment (Air, H2, and Ar). These findings suggest that a higher $d_0/D_0$-ratio not only affects the stress distribution in tensile test specimens but also impacts the embrittlement process. The study offers a valuable contribution for optimizing the design of test specimens for hydrogen embrittlement testing.