diff --git a/src/models.jl b/src/models.jl
index 780b1a6a6543df801a1974efb5cb8fff5cab58fc..965fd4e325f7517e0dff96adebba3a0e6c8855fb 100644
--- a/src/models.jl
+++ b/src/models.jl
@@ -234,7 +234,7 @@ function LarvaModel(id::LarvaID, timeseries::PlanarLarvae.TimeSeries{<:NamedTupl
     missingsteps = ones(Bool, steps[end])
     missingsteps[steps] .= false
     missingsteps = findall(missingsteps)
-    isempty(missingsteps) || @warn "Time steps are missing" id=string(id) missingsteps
+    isempty(missingsteps) || @warn "Time steps are missing" id=convert(Int, id) missingsteps
     path = coordinates.(larvatrack(timeseries))
     usertags = Observable(Dict{TimeStep, UserTags}())
     LarvaModel(id, alignedsteps, missingsteps, path, timeseries, usertags)
@@ -251,7 +251,7 @@ function LarvaModel(track::Track, times::Vector{PlanarLarvae.Time})
     missingsteps[steps] .= false
     missingsteps = findall(missingsteps)
     # this method may be dead code; the warning below has never been emitted
-    isempty(missingsteps) || @warn "Time steps are missing" id=string(track.id) missingsteps
+    isempty(missingsteps) || @warn "Time steps are missing" id=convert(Int, track.id) missingsteps
     path = coordinates.(larvatrack(track[:spine]))
     usertags = Observable(Dict{TimeStep, UserTags}())
     LarvaModel(track.id,