diff --git a/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/Commit.kt b/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/Commit.kt
deleted file mode 100644
index 9a8a1314d8..0000000000
--- a/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/Commit.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-package gov.nasa.jpl.aerie.scheduler.plan
-
-import gov.nasa.ammos.aerie.procedural.scheduling.plan.Edit
-import java.lang.ref.WeakReference
-
-data class Commit(
-  val diff: List<Edit>,
-
-  /**
-   * A record of the simulation results objects that were up-to-date when the commit
-   * was created.
-   *
-   * This has SHARED OWNERSHIP with [InMemoryEditablePlan]; the editable plan may add more to
-   * this list AFTER the commit is created.
-   */
-  val upToDateSimResultsSet: MutableSet<WeakReference<MerlinToProcedureSimulationResultsAdapter>>
-)
diff --git a/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/InMemoryEditablePlan.kt b/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/InMemoryEditablePlan.kt
index 1a8a3ffeee..049d7eb808 100644
--- a/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/InMemoryEditablePlan.kt
+++ b/scheduler-driver/src/main/kotlin/gov/nasa/jpl/aerie/scheduler/plan/InMemoryEditablePlan.kt
@@ -54,12 +54,25 @@ data class InMemoryEditablePlan(
     private val lookupActivityType: (String) -> ActivityType
 ) : EditablePlan, Plan by plan {
 
-  private val commits = mutableListOf<Commit>()
+  private data class Commit(
+    val diff: List<Edit>,
+
+    /**
+     * A record of the simulation results objects that were up-to-date when the commit
+     * was created.
+     *
+     * This has SHARED OWNERSHIP with [InMemoryEditablePlan]; the editable plan may add more to
+     * this list AFTER the commit is created.
+     */
+    val upToDateSimResultsSet: MutableSet<WeakReference<MerlinToProcedureSimulationResultsAdapter>>
+  )
+
+  private var committedChanges = Commit(listOf(), mutableSetOf())
   var uncommittedChanges = mutableListOf<Edit>()
     private set
 
   val totalDiff: List<Edit>
-    get() = commits.flatMap { it.diff }
+    get() = committedChanges.diff
 
   // Jointly owned set of up-to-date simulation results. See class-level comment for algorithm explanation.
   private var upToDateSimResultsSet: MutableSet<WeakReference<MerlinToProcedureSimulationResultsAdapter>> = mutableSetOf()
@@ -108,11 +121,11 @@ data class InMemoryEditablePlan(
     // Probably unnecessary, but shared ownership freaks me out enough already.
     if (uncommittedChanges.isEmpty()) return
 
-    val committedEdits = uncommittedChanges
+    val newCommittedChanges = uncommittedChanges
     uncommittedChanges = mutableListOf()
 
     // Create a commit that shares ownership of the simResults set.
-    commits.add(Commit(committedEdits, upToDateSimResultsSet))
+    committedChanges = Commit(committedChanges.diff + newCommittedChanges, upToDateSimResultsSet)
   }
 
   override fun rollback(): List<Edit> {
@@ -131,10 +144,10 @@ data class InMemoryEditablePlan(
     for (simResult in upToDateSimResultsSet) {
       simResult.get()?.stale = true
     }
-    for (simResult in commits.last().upToDateSimResultsSet) {
+    for (simResult in committedChanges.upToDateSimResultsSet) {
       simResult.get()?.stale = false
     }
-    upToDateSimResultsSet = commits.last().upToDateSimResultsSet
+    upToDateSimResultsSet = committedChanges.upToDateSimResultsSet
     return result
   }