diff --git a/server/etcdserver/memory_storage_test.go b/server/etcdserver/memory_storage_test.go
index bbbbc9787..19e61efc6 100644
--- a/server/etcdserver/memory_storage_test.go
+++ b/server/etcdserver/memory_storage_test.go
@@ -23,10 +23,9 @@ import (
 	"go.etcd.io/raft/v3/raftpb"
 )
 
-// TestMemoryStorageCompaction tests that after calling raftStorage.Compact(compacti)
-// without errors, the dummy entry becomes {Index: compacti} and
-// raftStorage.FirstIndex() returns (compacti+1, nil).
-func TestMemoryStorageCompaction(t *testing.T) {
+// TestMemoryStorageCompactInclusive tests that compacting is inclusive,
+// meaning the first index after compaction is larger by one than compacted index.
+func TestMemoryStorageCompactInclusive(t *testing.T) {
 	// entries: [ {Index: 0} ]
 	raftStorage := raft.NewMemoryStorage()
 
@@ -57,11 +56,12 @@ func TestMemoryStorageCompaction(t *testing.T) {
 
 	// after compacting, entries should be:
 	// [ {Index: 3}, {Index: 4}, {Index: 5} ]
-	err = raftStorage.Compact(3)
+	compacti := uint64(3)
+	err = raftStorage.Compact(compacti)
 	assert.NoError(t, err)
 
 
 	firstIndex, err = raftStorage.FirstIndex()
 	assert.NoError(t, err)
-	assert.Equal(t, uint64(3+1), firstIndex)
+	assert.Equal(t, compacti+1, firstIndex)
 }
diff --git a/server/etcdserver/server.go b/server/etcdserver/server.go
index 0463a175a..165a2a4c0 100644
--- a/server/etcdserver/server.go
+++ b/server/etcdserver/server.go
@@ -818,12 +818,9 @@ func (s *EtcdServer) run() {
 		snapi:     sn.Metadata.Index,
 		appliedt:  sn.Metadata.Term,
 		appliedi:  sn.Metadata.Index,
-		// compacti is the index from the last time raftStorage.Compact was called
-		// without errors.
-		//
-		// After calling raftStorage.Compact(compacti) without errors, the dummy entry of
-		// raftStorage becomes {Index: compacti}, and raftStorage.FirstIndex() returns
-		// (compacti+1, nil). This is validated by TestMemoryStorageCompaction.
+		// Compaction is inclusive, meaning compact index should be lower by one
+		// than the first index after compaction.
+		// This is validated by TestMemoryStorageCompaction.
 		compacti: firstRaftIndex - 1,
 	}