Brillouin optical time-domain reflectometry is used to perform distributed forward stimulated Brillouin scattering (FSBS) measurements. This configuration suppresses the need for an additional frequency scanning to evaluate the local Brillouin peak gain when probing the FSBS resonance. The use of a broad pass-band filter makes the system insensitive to moderate temperature or strain fluctuations, but enables to accurately retrieve any change in intensity due to FSBS.