diff --git a/src/accessiclock/audio/tts_engine.py b/src/accessiclock/audio/tts_engine.py
index e6f4f87..535161a 100644
--- a/src/accessiclock/audio/tts_engine.py
+++ b/src/accessiclock/audio/tts_engine.py
@@ -180,7 +180,9 @@ def _format_natural(self, hour: int, minute: int, am_pm: str) -> str:
             next_hour = hour % 12 + 1
             if next_hour == 0:
                 next_hour = 12
-            return f"quarter to {next_hour} {am_pm}"
+            # Flip AM/PM when crossing noon (12 PM) or midnight (12 AM)
+            next_am_pm = ("PM" if am_pm == "AM" else "AM") if hour == 11 else am_pm
+            return f"quarter to {next_hour} {next_am_pm}"
         else:
             return f"{hour}:{minute:02d} {am_pm}"
 
diff --git a/tests/test_tts_engine.py b/tests/test_tts_engine.py
index 8122bc0..ac98fa5 100644
--- a/tests/test_tts_engine.py
+++ b/tests/test_tts_engine.py
@@ -186,6 +186,36 @@ def test_format_time_natural_quarter_to(self):
         result = engine.format_time(time(14, 45), style="natural")
         assert "quarter to" in result.lower()
 
+    def test_format_time_natural_quarter_to_noon_boundary(self):
+        """At 11:45 AM, 'quarter to' should say 'quarter to 12 PM' not 'AM'."""
+        from accessiclock.audio.tts_engine import TTSEngine
+
+        engine = TTSEngine(force_dummy=True)
+        result = engine.format_time(time(11, 45), style="natural")
+        assert "quarter to" in result.lower()
+        assert "12" in result
+        assert "PM" in result
+
+    def test_format_time_natural_quarter_to_midnight_boundary(self):
+        """At 11:45 PM, 'quarter to' should say 'quarter to 12 AM' not 'PM'."""
+        from accessiclock.audio.tts_engine import TTSEngine
+
+        engine = TTSEngine(force_dummy=True)
+        result = engine.format_time(time(23, 45), style="natural")
+        assert "quarter to" in result.lower()
+        assert "12" in result
+        assert "AM" in result
+
+    def test_format_time_natural_quarter_to_no_boundary(self):
+        """At 2:45 PM, 'quarter to' should keep PM."""
+        from accessiclock.audio.tts_engine import TTSEngine
+
+        engine = TTSEngine(force_dummy=True)
+        result = engine.format_time(time(14, 45), style="natural")
+        assert "quarter to" in result.lower()
+        assert "3" in result
+        assert "PM" in result
+
     def test_format_time_natural_irregular_minute(self):
         """Natural style with irregular minutes should show time normally."""
         from accessiclock.audio.tts_engine import TTSEngine