diff --git a/sherlock_project/sherlock.py b/sherlock_project/sherlock.py
index e037d39458..c1c1b26ec1 100644
--- a/sherlock_project/sherlock.py
+++ b/sherlock_project/sherlock.py
@@ -227,6 +227,7 @@ def sherlock(
 
     # Results from analysis of all sites
     results_total = {}
+    request_futures = {}
 
     # First create futures for all requests. This allows for the requests to run in parallel
     for social_network, net_info in site_data.items():
@@ -333,7 +334,7 @@ def sherlock(
                 )
 
             # Store future in data for access later
-            net_info["request_future"] = future
+            request_futures[social_network] = future
 
         # Add this site's results into final dictionary with all the other results.
         results_total[social_network] = results_site
@@ -356,7 +357,7 @@ def sherlock(
             error_type: list[str] = [error_type]
 
         # Retrieve future and ensure it has finished
-        future = net_info["request_future"]
+        future = request_futures[social_network]
         r, error_text, exception_text = get_response(
             request_future=future, error_type=error_type, social_network=social_network
         )
diff --git a/tests/test_ux.py b/tests/test_ux.py
index 1feaf88a19..44cab0c487 100644
--- a/tests/test_ux.py
+++ b/tests/test_ux.py
@@ -1,5 +1,6 @@
 import pytest
 from sherlock_project import sherlock
+from sherlock_project.notify import QueryNotify
 from sherlock_interactives import Interactives
 from sherlock_interactives import InteractivesSubprocessError
 
@@ -33,6 +34,50 @@ def test_wildcard_username_expansion():
     assert sherlock.multiple_usernames('test{?}test') == ["test_test" , "test-test" , "test.test"]
 
 
+def test_sherlock_does_not_mutate_input_site_data(monkeypatch):
+    class FakeResponse:
+        status_code = 404
+        text = ""
+        encoding = "UTF-8"
+        elapsed = None
+
+    class FakeFuture:
+        def result(self):
+            return FakeResponse()
+
+    class FakeFuturesSession:
+        def __init__(self, *args, **kwargs):
+            pass
+
+        def head(self, **kwargs):
+            return FakeFuture()
+
+        get = head
+        post = head
+        put = head
+
+    monkeypatch.setattr(sherlock.requests, "session", lambda: object())
+    monkeypatch.setattr(sherlock, "SherlockFuturesSession", FakeFuturesSession)
+    site_data = {
+        "Example": {
+            "urlMain": "https://example.com",
+            "url": "https://example.com/{}",
+            "errorType": "status_code",
+            "errorCode": 404,
+        }
+    }
+    original_site_data = {name: dict(info) for name, info in site_data.items()}
+
+    sherlock.sherlock(
+        username="alice",
+        site_data=site_data,
+        query_notify=QueryNotify(),
+        timeout=1,
+    )
+
+    assert site_data == original_site_data
+
+
 @pytest.mark.parametrize('cliargs', [
     '',
     '--site urghrtuight --egiotr',