  We have performed a detailed spectral analysis of the helium-rich hot
subdwarf EC 20187-4939 using data obtained in the SALT survey of helium-rich
hot subdwarfs. We have measured its effective temperature, surface gravity and
chemical abundances from the spectrum. Its radius has also been determined by
fitting the spectral energy distribution using photometric data, from which a
mass of 0.44 Msun has been inferred using the measurement of surface gravity.
This star is particularly abundant in helium and nitrogen, whilst being both
carbon and oxygen-weak. The surface abundances and mass have been found to be
consistent with a helium white dwarf merger product. The abundance effects of
alpha captures on nitrogen during the merger process and possible connections
between EC 20187-4939 and other carbon-weak related objects are discussed.
