diff --git a/tests/test_prefix_matching.py b/tests/test_prefix_matching.py
index 0b77dbd..adf73ac 100644
--- a/tests/test_prefix_matching.py
+++ b/tests/test_prefix_matching.py
@@ -40,16 +40,18 @@ async def dummy_handler(player, args):
     await player.writer.drain()
 
 
-@pytest.fixture(autouse=True)
+@pytest.fixture
 def clean_registry():
     """Clear registry before each test."""
+    original_registry = commands._registry.copy()
     commands._registry.clear()
     yield
     commands._registry.clear()
+    commands._registry.update(original_registry)
 
 
 @pytest.mark.asyncio
-async def test_exact_match_still_works(player):
+async def test_exact_match_still_works(player, clean_registry):
     """Test that exact matches work as before."""
     commands.register(
         CommandDefinition(name="look", handler=dummy_handler, mode="normal")
@@ -63,7 +65,7 @@ async def test_exact_match_still_works(player):
 
 
 @pytest.mark.asyncio
-async def test_prefix_match_resolves_unique_prefix(player):
+async def test_prefix_match_resolves_unique_prefix(player, clean_registry):
     """Test that a unique prefix resolves to the full command."""
     commands.register(
         CommandDefinition(name="sweep", handler=dummy_handler, mode="normal")
@@ -77,7 +79,7 @@ async def test_prefix_match_resolves_unique_prefix(player):
 
 
 @pytest.mark.asyncio
-async def test_ambiguous_prefix_two_matches(player):
+async def test_ambiguous_prefix_two_matches(player, clean_registry):
     """Test that ambiguous prefix with 2 matches shows 'A or B?' message."""
     commands.register(
         CommandDefinition(name="swoop", handler=dummy_handler, mode="normal")
@@ -95,7 +97,7 @@ async def test_ambiguous_prefix_two_matches(player):
 
 
 @pytest.mark.asyncio
-async def test_ambiguous_prefix_three_plus_matches(player):
+async def test_ambiguous_prefix_three_plus_matches(player, clean_registry):
     """Test that ambiguous prefix with 3+ matches shows comma-separated."""
     commands.register(
         CommandDefinition(name="send", handler=dummy_handler, mode="normal")
@@ -119,7 +121,7 @@ async def test_ambiguous_prefix_three_plus_matches(player):
 
 
 @pytest.mark.asyncio
-async def test_no_match_shows_unknown_command(player):
+async def test_no_match_shows_unknown_command(player, clean_registry):
     """Test that no match shows unknown command message."""
     commands.register(
         CommandDefinition(name="look", handler=dummy_handler, mode="normal")
@@ -133,7 +135,7 @@ async def test_no_match_shows_unknown_command(player):
 
 
 @pytest.mark.asyncio
-async def test_exact_alias_match_wins_over_prefix(player):
+async def test_exact_alias_match_wins_over_prefix(player, clean_registry):
     """Test that exact match on alias takes priority over prefix match."""
     commands.register(
         CommandDefinition(
@@ -156,7 +158,7 @@ async def test_exact_alias_match_wins_over_prefix(player):
 
 
 @pytest.mark.asyncio
-async def test_single_char_ambiguous_prefix(player):
+async def test_single_char_ambiguous_prefix(player, clean_registry):
     """Test that single-char ambiguous prefix shows disambiguation."""
     commands.register(
         CommandDefinition(name="quit", handler=dummy_handler, mode="normal")
@@ -173,7 +175,7 @@ async def test_single_char_ambiguous_prefix(player):
 
 
 @pytest.mark.asyncio
-async def test_prefix_match_deduplicates_aliases(player):
+async def test_prefix_match_deduplicates_aliases(player, clean_registry):
     """Test that aliases to the same command don't create multiple matches."""
     commands.register(
         CommandDefinition(
@@ -201,7 +203,7 @@ async def test_prefix_match_deduplicates_aliases(player):
 
 
 @pytest.mark.asyncio
-async def test_prefix_match_with_args(player):
+async def test_prefix_match_with_args(player, clean_registry):
     """Test that prefix matching preserves arguments."""
     commands.register(
         CommandDefinition(name="sweep", handler=dummy_handler, mode="normal")