diff --git a/chain_commands.go b/chain_commands.go
index aaa6b90..5a27ac1 100644
--- a/chain_commands.go
+++ b/chain_commands.go
@@ -30,6 +30,7 @@ const chainExplorerCommandName = "explorer"
 const chainSyncCommandName = "sync"
 const defaultChainSeed = "seeds.lthn.io:36942"
 const defaultChainTestnetSeed = "localhost:46942"
+const defaultChainDataDirHelp = "store chain data and sync state in this directory (defaults to ~/.lethean/chain, or ~/.lethean/testnet/chain with --testnet)"
 const chainCommandPath = AppName + " " + ChainCommandName
 const chainExplorerCommandPath = chainCommandPath + " " + chainExplorerCommandName
 const chainSyncCommandPath = chainCommandPath + " " + chainSyncCommandName
@@ -71,7 +72,7 @@ func AddChainCommands(root *cobra.Command) {
 		Args:    cobra.NoArgs,
 	}
 
-	chainCmd.PersistentFlags().StringVar(&dataDir, "data-dir", defaultChainDataDirPath(), "store chain data and sync state in this directory")
+	chainCmd.PersistentFlags().StringVar(&dataDir, "data-dir", defaultChainDataDirPath(), defaultChainDataDirHelp)
 	chainCmd.PersistentFlags().StringVar(&seed, "seed", defaultChainSeed, "connect to this seed peer first (host:port)")
 	chainCmd.PersistentFlags().BoolVar(&testnet, "testnet", false, "use the Lethean testnet and its default seed ("+defaultChainTestnetSeed+")")
 
@@ -94,10 +95,17 @@ func chainConfigForSeed(testnet bool, seed string) (config.ChainConfig, []config
 }
 
 func defaultChainDataDirPath() string {
+	return defaultChainDataDirPathForNetwork(false)
+}
+
+func defaultChainDataDirPathForNetwork(testnet bool) string {
 	home, err := os.UserHomeDir()
 	if err != nil {
 		return ".lethean"
 	}
+	if testnet {
+		return filepath.Join(home, ".lethean", "testnet", "chain")
+	}
 	return filepath.Join(home, ".lethean", "chain")
 }
 
@@ -123,6 +131,13 @@ func resolveChainDataDir(dataDir string) (string, error) {
 	return filepath.Clean(dataDir), nil
 }
 
+func resolveChainCommandDataDir(dataDir string, testnet, explicit bool) (string, error) {
+	if !explicit {
+		dataDir = defaultChainDataDirPathForNetwork(testnet)
+	}
+	return resolveChainDataDir(dataDir)
+}
+
 func ensureChainDataDirExists(dataDir string) error {
 	if err := coreio.Local.EnsureDir(dataDir); err != nil {
 		return coreerr.E("ensureChainDataDirExists", "create data dir", err)
diff --git a/commands_test.go b/commands_test.go
index 04c38d7..f0bec52 100644
--- a/commands_test.go
+++ b/commands_test.go
@@ -129,6 +129,24 @@ func TestResolveChainDataDir_Good_ExpandsEnvVars(t *testing.T) {
 	assert.Equal(t, "/tmp/lethean/node", got)
 }
 
+func TestResolveChainCommandDataDir_Good_UsesMainnetDefaultWhenImplicit(t *testing.T) {
+	got, err := resolveChainCommandDataDir(defaultChainDataDirPath(), false, false)
+	require.NoError(t, err)
+	assert.Equal(t, defaultChainDataDirPathForNetwork(false), got)
+}
+
+func TestResolveChainCommandDataDir_Good_UsesTestnetDefaultWhenImplicit(t *testing.T) {
+	got, err := resolveChainCommandDataDir(defaultChainDataDirPath(), true, false)
+	require.NoError(t, err)
+	assert.Equal(t, defaultChainDataDirPathForNetwork(true), got)
+}
+
+func TestResolveChainCommandDataDir_Good_KeepsExplicitDataDirOnTestnet(t *testing.T) {
+	got, err := resolveChainCommandDataDir("/tmp/custom-chain", true, true)
+	require.NoError(t, err)
+	assert.Equal(t, "/tmp/custom-chain", got)
+}
+
 func TestValidateChainSyncModeSelection_Good(t *testing.T) {
 	err := validateChainSyncModeSelection(true, false)
 	require.NoError(t, err)
@@ -223,7 +241,7 @@ func TestAddChainCommands_Good_PersistentFlagHelp(t *testing.T) {
 
 	chainCmd, _, _ := root.Find([]string{ChainCommandName})
 
-	assert.Equal(t, "store chain data and sync state in this directory", chainCmd.PersistentFlags().Lookup("data-dir").Usage)
+	assert.Equal(t, defaultChainDataDirHelp, chainCmd.PersistentFlags().Lookup("data-dir").Usage)
 	assert.Equal(t, "connect to this seed peer first (host:port)", chainCmd.PersistentFlags().Lookup("seed").Usage)
 	assert.Equal(t, "use the Lethean testnet and its default seed (localhost:46942)", chainCmd.PersistentFlags().Lookup("testnet").Usage)
 }
diff --git a/explorer_command.go b/explorer_command.go
index 9939ddd..e090ce3 100644
--- a/explorer_command.go
+++ b/explorer_command.go
@@ -40,7 +40,11 @@ func newChainExplorerCommand(dataDir, seed *string, testnet *bool) *cobra.Comman
 		Example: chainExplorerExample,
 		Args:    cobra.NoArgs,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return runChainExplorer(*dataDir, *seed, *testnet)
+			resolvedDataDir, err := resolveChainCommandDataDir(*dataDir, *testnet, cmd.Flags().Changed("data-dir"))
+			if err != nil {
+				return err
+			}
+			return runChainExplorer(resolvedDataDir, *seed, *testnet)
 		},
 	}
 }
diff --git a/sync_command.go b/sync_command.go
index 341502f..fb92d8a 100644
--- a/sync_command.go
+++ b/sync_command.go
@@ -47,16 +47,20 @@ func newChainSyncCommand(dataDir, seed *string, testnet *bool) *cobra.Command {
 		Example: chainSyncExample,
 		Args:    cobra.NoArgs,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			resolvedDataDir, err := resolveChainCommandDataDir(*dataDir, *testnet, cmd.Flags().Changed("data-dir"))
+			if err != nil {
+				return err
+			}
 			if err := validateChainSyncModeSelection(runAsDaemon, stopDaemon); err != nil {
 				return err
 			}
 			if stopDaemon {
-				return stopChainSyncDaemon(*dataDir)
+				return stopChainSyncDaemon(resolvedDataDir)
 			}
 			if runAsDaemon {
-				return runChainSyncDaemon(*dataDir, *seed, *testnet)
+				return runChainSyncDaemon(resolvedDataDir, *seed, *testnet)
 			}
-			return runChainSyncForeground(*dataDir, *seed, *testnet)
+			return runChainSyncForeground(resolvedDataDir, *seed, *testnet)
 		},
 	}
 
diff --git a/tui/status_model.go b/tui/status_model.go
index ac6d405..b04635a 100644
--- a/tui/status_model.go
+++ b/tui/status_model.go
@@ -49,7 +49,7 @@ func (m *StatusModel) Update(msg tea.Msg) (cli.FrameModel, tea.Cmd) {
 // not yet received a status snapshot, so it shows a placeholder.
 func (m *StatusModel) View(width, height int) string {
 	var line string
-	if height == 0 {
+	if m.status.Height == 0 {
 		line = " height 0 | syncing..."
 	} else {
 		s := m.status
diff --git a/tui/status_model_test.go b/tui/status_model_test.go
index cc22627..0d68f77 100644
--- a/tui/status_model_test.go
+++ b/tui/status_model_test.go
@@ -17,8 +17,8 @@ func TestStatusModel_View_Good_Initial(t *testing.T) {
 	m := NewStatusModel(n)
 
 	got := m.View(80, 1)
-	if !strings.Contains(got, "syncing") && !strings.Contains(got, "0") {
-		t.Errorf("initial View should contain \"syncing\" or \"0\", got %q", got)
+	if !strings.Contains(got, "syncing") {
+		t.Errorf("initial View should contain \"syncing\", got %q", got)
 	}
 }