diff --git a/eventstore/mmm/fuzz_test.go b/eventstore/mmm/fuzz_test.go
index 55375fa..725bd8e 100644
--- a/eventstore/mmm/fuzz_test.go
+++ b/eventstore/mmm/fuzz_test.go
@@ -40,7 +40,9 @@ func FuzzTest(f *testing.F) {
 
 		for i := range nlayers {
 			name := string([]byte{97 + byte(i)})
-			err = mmmm.EnsureLayer(name, &IndexingLayer{})
+			il := &IndexingLayer{}
+			err = mmmm.EnsureLayer(name, il)
+			defer il.Close()
 			require.NoError(t, err, "layer %s/%d", name, i)
 		}
 
diff --git a/eventstore/mmm/mmmm.go b/eventstore/mmm/mmmm.go
index d6b2c12..3c87863 100644
--- a/eventstore/mmm/mmmm.go
+++ b/eventstore/mmm/mmmm.go
@@ -329,4 +329,6 @@ func (b *MultiMmapManager) Close() {
 	for _, il := range b.layers {
 		il.Close()
 	}
+
+	syscall.Munmap(b.mmapf)
 }