diff --git a/src/motility.jl b/src/motility.jl
index b8db7df..f5a0baa 100644
--- a/src/motility.jl
+++ b/src/motility.jl
@@ -5,7 +5,7 @@ export motilepattern, motilestate, state, states, transition_weights
 export duration, speed, polar, azimuthal
 export Arccos # from Agents
 
-@compact_structs MotileState begin
+@sum_structs MotileState begin
     @kwdef struct RunState
         duration
         speed