diff --git a/packages/validator/src/services/proposerPreferences.ts b/packages/validator/src/services/proposerPreferences.ts
index 29e161754156..42ff1101bb5a 100644
--- a/packages/validator/src/services/proposerPreferences.ts
+++ b/packages/validator/src/services/proposerPreferences.ts
@@ -47,6 +47,7 @@ export class ProposerPreferencesService {
     _metrics: Metrics | null
   ) {
     clock.runEverySlot(this.runProposerPreferencesTask);
+    clock.runEveryEpoch(this.pruneSubmitted);
   }
 
   private runProposerPreferencesTask = async (slot: Slot): Promise<void> => {
@@ -128,4 +129,13 @@ export class ProposerPreferencesService {
       this.logger.error("Error submitting signed proposer preferences", {count: batch.length}, e as Error);
     }
   };
+
+  /** Drop tracking for past epochs; only currentEpoch and currentEpoch + 1 are ever processed. */
+  private pruneSubmitted = async (epoch: Epoch): Promise<void> => {
+    for (const trackedEpoch of this.submitted.keys()) {
+      if (trackedEpoch < epoch) {
+        this.submitted.delete(trackedEpoch);
+      }
+    }
+  };
 }