diff --git a/CHANGELOG.md b/CHANGELOG.md
index 41a73ab..0b8b303 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,9 @@
 # Changes
 
 - Ensure that curated path and incoming path definitions do not point
-  outside of the storage-root tree.
+  outside the storage-root tree.
+
+- Ensure that default tokens cannot be deleted.
 
 
 # 6.3.2 (2026-07-07)
diff --git a/dump_things_service/tests/test_token_endpoints.py b/dump_things_service/tests/test_token_endpoints.py
index 0af5019..fd66941 100644
--- a/dump_things_service/tests/test_token_endpoints.py
+++ b/dump_things_service/tests/test_token_endpoints.py
@@ -1,4 +1,4 @@
-from starlette.status import HTTP_409_CONFLICT
+from starlette.status import HTTP_406_NOT_ACCEPTABLE, HTTP_409_CONFLICT
 
 from dump_things_service import HTTP_201_CREATED
 
@@ -40,3 +40,14 @@ def test_token_creation(fastapi_client_simple):
         json=json_record,
     )
     assert response.status_code == HTTP_409_CONFLICT
+
+
+def test_default_token_removal(fastapi_client_simple):
+    test_client, _, admin_token = fastapi_client_simple
+
+    # Create a token with name 'a'
+    response = test_client.delete(
+        '/tokens/test_default_token',
+        headers={'x-dumpthings-token': admin_token},
+    )
+    assert response.status_code == HTTP_406_NOT_ACCEPTABLE
diff --git a/dump_things_service/token_endpoints.py b/dump_things_service/token_endpoints.py
index 8f8d5d8..8cea286 100644
--- a/dump_things_service/token_endpoints.py
+++ b/dump_things_service/token_endpoints.py
@@ -266,7 +266,20 @@ async def delete_token_with_name(
         detail = f"token with name '{token_name}' does not exist."
         raise HTTPException(status_code=HTTP_404_NOT_FOUND, detail=detail)
 
-    # Store the new token in the configuration
+    # Check that the token is not a default token of a collection
+    default_tokens = {
+        collection_info.default_token: collection_name
+        for collection_name, collection_info in abstract_config.collections.items()
+    }
+    if token_name in default_tokens:
+        detail = (
+            f"token with name '{token_name}' cannot be deleted because"
+            'it is the default token for collection '
+            f"'{default_tokens[token_name]}'."
+        )
+        raise HTTPException(status_code=HTTP_406_NOT_ACCEPTABLE, detail=detail)
+
+    # Delete the token from the configuration
     del abstract_config.tokens[token_name]
 
     # Manifest the new configuration