diff --git a/src/onset.jl b/src/onset.jl
index 5e7d364a..29530fce 100644
--- a/src/onset.jl
+++ b/src/onset.jl
@@ -65,7 +65,7 @@ function simulate_onsets(rng, onset::AbstractOnset, simulation::Simulation)
     onsets = simulate_interonset_distances(rng, onset, simulation.design)
 
     # accumulate them
-    onsets_accum = accumulate(+, onsets, dims = 1)
+    onsets_accum = accumulate(+, onsets, dims = 1, init = 1)
 
     return onsets_accum
 end
diff --git a/test/onset.jl b/test/onset.jl
index 7d46908f..9865a32c 100644
--- a/test/onset.jl
+++ b/test/onset.jl
@@ -46,7 +46,7 @@
         @test minimum(rand_vec) >= 0
     end
     @testset "sim_onsets" begin
-        # test accumulate always increasing
+        
         uniform_onset = UniformOnset(; offset = 0, width = 50)
 
         accumulated_onset = UnfoldSim.simulate_onsets(
@@ -54,7 +54,11 @@
             uniform_onset,
             gen_debug_simulation(onset = uniform_onset),
         )
+        # test accumulate always increasing
         @test all(diff(accumulated_onset, dims = 1) .>= 0)
+
+        # test that the first onset is at >=1 (not 0)
+        @test accumulated_onset[1] >= 1
     end
 
 end