Power line communication (PLC) utilizes power lines for the purpose of electronic data transmission. Differential binary phase shift keying (DBPSK) is a popular modulation scheme proposed in the PLC standards like G3, PRIME, and IEEE P1901.2. This letter provides the performance evaluation of a PLC system assuming DBPSK modulation under the combined effect of Nakagami-m background noise and impulsive noise. We utilize a simple, yet accurate approximation available in literature to derive the probability density function of the sum of two Nakagami-m random variables. Closed-form expressions of the analytical average bit error rate and the outage probability of the system are derived. Validity of the derived analytical expressions is closely verified by simulated results. © 2016 IEEE.