diff --git a/lcviz/plugins/ephemeris/ephemeris.py b/lcviz/plugins/ephemeris/ephemeris.py
index 3b9f89d7..1defaa20 100644
--- a/lcviz/plugins/ephemeris/ephemeris.py
+++ b/lcviz/plugins/ephemeris/ephemeris.py
@@ -100,7 +100,8 @@ def __init__(self, *args, **kwargs):
                                                        manual_options=['default'],
                                                        on_add=self._on_component_add,
                                                        on_rename_after_selection=self._on_component_rename,  # noqa
-                                                       on_remove_after_selection=self._on_component_remove)  # noqa
+                                                       on_remove_after_selection=self._on_component_remove,  # noqa
+                                                       validate_choice=self._validate_component)
 
         # force the original entry in ephemerides with defaults
         self._change_component()
@@ -311,6 +312,13 @@ def _check_if_phase_viewer_exists(self, *args):
         viewer_base_refs = [id.split('[')[0] for id in self.app.get_viewer_ids()]
         self.phase_viewer_exists = self.phase_viewer_id in viewer_base_refs
 
+    def _validate_component(self, lbl):
+        if '[' in lbl or ']' in lbl:
+            return 'cannot contain square brackets'
+        if ':' in lbl:
+            return 'cannot contain colon'
+        return ''
+
     def _on_component_add(self, lbl):
         self.hub.broadcast(EphemerisComponentChangedMessage(old_lbl=None, new_lbl=lbl,
                                                             sender=self))
diff --git a/lcviz/tests/test_plugin_ephemeris.py b/lcviz/tests/test_plugin_ephemeris.py
index 9953f2af..d5e6cac9 100644
--- a/lcviz/tests/test_plugin_ephemeris.py
+++ b/lcviz/tests/test_plugin_ephemeris.py
@@ -1,3 +1,9 @@
+import pytest
+from packaging.version import Version
+
+import jdaviz
+JDAVIZ_LT_3_9_0 = Version(jdaviz.__version__) < Version('3.9.0')
+
 
 def test_docs_snippets(helper, light_curve_like_kepler_quarter):
     lcviz, lc = helper, light_curve_like_kepler_quarter
@@ -43,6 +49,14 @@ def test_plugin_ephemeris(helper, light_curve_like_kepler_quarter):
     assert len(ephem.ephemerides) == 2
     assert 'custom component' in ephem.ephemerides
 
+    if not JDAVIZ_LT_3_9_0:
+        with pytest.raises(ValueError):
+            # brackets interfere with cloned viewer label logic
+            ephem.rename_component('custom component', 'custom component[blah]')
+        with pytest.raises(ValueError):
+            # colons interfere with viewer ephemeris logic
+            ephem.rename_component('custom component', 'custom component:blah')
+
     ephem.rename_component('custom component', 'renamed custom component')
     assert len(ephem.ephemerides) == 2
     assert 'renamed custom component' in ephem.ephemerides