diff --git a/news.d/bugfix/1547.core.md b/news.d/bugfix/1547.core.md
new file mode 100644
index 000000000..b4b9885f4
--- /dev/null
+++ b/news.d/bugfix/1547.core.md
@@ -0,0 +1 @@
+Fix possible exception when calling `Engine.clear_translator_state(undo=True)`.
diff --git a/plover/engine.py b/plover/engine.py
index b3682fb68..5ac8371fa 100644
--- a/plover/engine.py
+++ b/plover/engine.py
@@ -527,7 +527,8 @@ def translator_state(self, state):
     def clear_translator_state(self, undo=False):
         if undo:
             state = self._translator.get_state()
-            self._formatter.format(state.translations, (), None)
+            if state.translations:
+                self._formatter.format(state.translations, (), None)
         self._translator.clear_state()
 
     @property
diff --git a/test/test_engine.py b/test/test_engine.py
index 086224f0e..6c835a794 100644
--- a/test/test_engine.py
+++ b/test/test_engine.py
@@ -264,3 +264,6 @@ def test_engine_running_state(engine):
     # Running state is kept throughout.
     engine.set_output(True)
     assert engine.translator_state == running_state
+
+def test_undo_and_clear_empty_translator_state(engine):
+    engine.clear_translator_state(undo=True)