We tested the hypothesis that phonological planning takes longer when two possible utterances differ in incompatible, inherently mutually exclusive values of a single feature (e.g., voiced vs. unvoiced, a dental vs. alveolar tongue-tip constriction) compared to when two possible utterances differ in values for features that are not inherently mutually exclusive (e.g., a tongue-tip constriction vs. a labial constriction). Verbal acoustic latencies from a cue-response task were analyzed. When the mutually exclusive feature value was voicing in plosive-intial utterances, latencies were in fact shorter than when articulator was unknown, contra expectation. When the mutually exclusive feature value was voicing in fricative-intial utterances, there was no reliable difference in latencies. When the mutually exclusive feature value was tongue-tip constriction location, latency differences were as expected, albeit marginally. These results suggest that the notion of inherently mutually exclusive feature values requires further refinement, and may depend on specific aspects of phonological representation.