Saramaccan is an Atlantic English creole with substratal tonal features, including high tone spread. While high tone spread is generally leftward, an analysis of rightward spread accounts for the data in serial verb constructions where there are high tones that cannot be explained by leftward spread. However, there are other serial verb constructions with high tones that can be explained by leftward spread. There are two sets of high tone spread rules, then, but rightward spread is basically limited to constructions that are unequivocally of substrate origin, namely serial verb constructions. Significantly, while the origin of leftward spread is unknown, the primary substrate language Fongbe has rightward high tone spread, and is the apparent source of Saramaccan serial verb constructions. This uniquely substrate construction, then, may have transferred with its own rightward tone spread rules, which adapted to leftward tone spread rules resulting in rightward tone spread rules in Saramaccan that are more complex than the source.