Casting a ballot for a losing candidate or party clearly limits one's capacity to influence political outcomes. An increase in wasted votes implies that more preferences end up not being represented, and thus political inequality levels rise. This paper aims at assessing whether the social profile of those who waste their vote is dependent upon the institutional setting of elections. More precisely, we test for the effect of electoral district magnitude on the proportion of wasted votes and how it generates inequality of voice between voters. We estimate multilevel logistic regression models for 52 electoral districts in Spain using data from the 2015 parliamentary elections. Significant variation in district magnitude particular to the Spanish electoral system allows us to test our theory for proportional representation, mixed, and majoritarian subsystems in a single case study. Our results demonstrate that wasted votes indeed aggravate the political inequality of citizens of different profile dependent upon the level of proportionality of electoral rule. Moreover, wasted votes do not only lay the ground for unequal representation, but they also make the disadvantaged part of the constituency call into question the legitimacy of the political system.