diff --git a/src/ReCo.jl b/src/ReCo.jl
index 75b2e95..48333b3 100644
--- a/src/ReCo.jl
+++ b/src/ReCo.jl
@@ -10,7 +10,7 @@ using JLD2: JLD2
 using JSON3: JSON3
 
 import Dates: now, CompoundPeriod, canonicalize
-import Base: push!, iterate
+import Base: push!, iterate, wait
 
 # BEGIN dev deps
 using Revise
diff --git a/src/data.jl b/src/data.jl
index d61b915..320a02a 100644
--- a/src/data.jl
+++ b/src/data.jl
@@ -49,10 +49,10 @@ function set_status(dir::String, n_bundles::Int64, T::Float64)
 end
 
 function save_bundle(dir::String, bundle::Bundle, n::Int64, T::Float64)
-    bundle_dir = "$dir/bundles/bundle$n"
-    mkpath(bundle_dir)
+    bundles_dir = "$dir/bundles"
+    mkpath(bundles_dir)
 
-    JLD2.save_object("$bundle_dir/bundle.jld2", bundle)
+    JLD2.save_object("$bundles_dir/bundle_$n.jld2", bundle)
 
     set_status(dir, n, T)
 
diff --git a/src/run.jl b/src/run.jl
index cd190c9..fcae647 100644
--- a/src/run.jl
+++ b/src/run.jl
@@ -81,13 +81,13 @@ function run_sim(
 
     n_bundles::Int64 = status.n_bundles
     next_bundle = n_bundles + 1
-    next_bundle_path = "$dir/bundles/bundle$next_bundle"
-    mkpath(next_bundle_path)
+    bundles_path = "$dir/bundles"
+    mkpath(bundles_path)
 
     if n_bundle_snapshots > 0
         save_data = true
 
-        open("$next_bundle_path/run_vars.json", "w") do f
+        open("$bundles_dir/run_vars_$next_bundle.json", "w") do f
             JSON3.pretty(f, run_vars)
         end
     else
diff --git a/src/simulation.jl b/src/simulation.jl
index 9e06308..f6c9085 100644
--- a/src/simulation.jl
+++ b/src/simulation.jl
@@ -63,6 +63,8 @@ function euler!(args)
     return nothing
 end
 
+wait(n::Nothing) = n
+
 function simulate(
     args,
     δt::Float64,
@@ -79,16 +81,21 @@ function simulate(
     start_time = now()
     println("Started simulation at $start_time.")
 
+    task::Union{Task,Nothing} = nothing
+
     @showprogress 0.6 for (integration_step, t) in enumerate(T0:δt:T)
         if (integration_step % n_steps_before_snapshot == 0) && save_data
+            wait(task)
             bundle_snapshot_counter += 1
             save_snapshot!(args.bundle, bundle_snapshot_counter, t, args.particles)
 
             if bundle_snapshot_counter == args.n_bundle_snapshots
-                bundle_snapshot_counter = 0
-                n_bundles += 1
+                task = @async begin
+                    bundle_snapshot_counter = 0
+                    n_bundles += 1
 
-                save_bundle(dir, args.bundle, n_bundles, t)
+                    save_bundle(dir, args.bundle, n_bundles, t)
+                end
             end
         end