diff --git a/fuzz/worker.go b/fuzz/worker.go
index c3f4d74..d8cc10d 100644
--- a/fuzz/worker.go
+++ b/fuzz/worker.go
@@ -632,6 +632,9 @@ func (ws *workerServer) fuzz(ctx context.Context, args fuzzArgs) (resp fuzzRespo
 		resp.Count = mem.header().count
 		ws.memMu <- mem
 	}()
+	if args.Limit > 0 && mem.header().count >= args.Limit {
+		panic(fmt.Sprintf("mem.header().count %d already exceeds args.Limit %d", mem.header().count, args.Limit))
+	}
 
 	vals, err := unmarshalCorpusFile(mem.valueCopy())
 	if err != nil {
diff --git a/fuzz/worker_test.go b/fuzz/worker_test.go
index 10d61b1..b536b3d 100644
--- a/fuzz/worker_test.go
+++ b/fuzz/worker_test.go
@@ -25,6 +25,11 @@ func BenchmarkWorkerFuzzOverhead(b *testing.B) {
 	if err != nil {
 		b.Fatalf("failed to create temporary shared memory file: %s", err)
 	}
+	defer func() {
+		if err := mem.Close(); err != nil {
+			b.Error(err)
+		}
+	}()
 
 	initialVal := []interface{}{make([]byte, 32)}
 	encodedVals := marshalCorpusFile(initialVal...)
@@ -36,6 +41,7 @@ func BenchmarkWorkerFuzzOverhead(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		ws.m = newMutator()
 		mem.setValue(encodedVals)
+		mem.header().count = 0
 
 		ws.fuzz(context.Background(), fuzzArgs{Limit: 1})
 	}