diff --git a/fuzz_lightyear/datastore.py b/fuzz_lightyear/datastore.py
index cb3e7fe..39070fb 100644
--- a/fuzz_lightyear/datastore.py
+++ b/fuzz_lightyear/datastore.py
@@ -46,6 +46,12 @@ def get_non_vulnerable_operations() -> Dict[str, Optional[str]]:
     return {}
 
 
+def clear_cache():
+    """ Clear the cached values for fixture functions """
+    for value in get_user_defined_mapping().values():
+        value._fuzz_cache = None
+
+
 def inject_user_defined_variables(func: Callable) -> Callable:
     """
     This decorator allows the use of user defined variables in functions.
@@ -62,6 +68,9 @@ def inject_user_defined_variables(func: Callable) -> Callable:
 
     @wraps(func)
     def wrapped(*args, **kwargs) -> Any:
+        if getattr(func, '_fuzz_cache', None) is not None:
+            return func._fuzz_cache  # type: ignore
+
         expected_args = _get_injectable_variables(func)
         type_annotations = inspect.getfullargspec(func).annotations
 
@@ -72,19 +81,22 @@ def wrapped(*args, **kwargs) -> Any:
                 # two values for the same argument.
                 continue
 
-            if arg_name not in kwargs and arg_name in mapping:
-                value = mapping[arg_name]()
-                if (
-                    arg_name in type_annotations and
-                    not isinstance(type_annotations[arg_name], type(List))
-                ):
-                    # If type annotations are used, use that to cast
-                    # values for input.
-                    value = type_annotations[arg_name](value)
+            if arg_name not in mapping:
+                raise TypeError
+
+            value = mapping[arg_name]()
+            if (
+                arg_name in type_annotations and
+                not isinstance(type_annotations[arg_name], type(List))
+            ):
+                # If type annotations are used, use that to cast
+                # values for input.
+                value = type_annotations[arg_name](value)
 
-                kwargs[arg_name] = value
+            kwargs[arg_name] = value
 
-        return func(*args, **kwargs)
+        func._fuzz_cache = func(*args, **kwargs)  # type: ignore
+        return func._fuzz_cache  # type: ignore
 
     return wrapped
 
diff --git a/fuzz_lightyear/runner.py b/fuzz_lightyear/runner.py
index da93b79..6abb4fb 100644
--- a/fuzz_lightyear/runner.py
+++ b/fuzz_lightyear/runner.py
@@ -1,5 +1,6 @@
 from typing import List
 
+from .datastore import clear_cache
 from .request import FuzzingRequest
 from .response import ResponseSequence
 
@@ -15,4 +16,5 @@ def run_sequence(
 
     # Then, check for vulnerabilities.
     responses.analyze_requests(sequence)
+    clear_cache()
     return responses
diff --git a/tests/integration/supplements/factory_integration_test.py b/tests/integration/supplements/factory_integration_test.py
index 8361f33..64a07f5 100644
--- a/tests/integration/supplements/factory_integration_test.py
+++ b/tests/integration/supplements/factory_integration_test.py
@@ -16,3 +16,33 @@ def factory():
 
     assert request.fuzzed_input['string'] == '1'
     assert request.fuzzed_input['integer'] == 1
+
+
+def test_session_fixtures(mock_client):
+    count = 0
+
+    def nested_function():
+        nonlocal count
+        count += 1
+        return count
+
+    def child_a(nested):
+        return nested
+
+    def child_b(nested):
+        return nested
+
+    def function(a, b):
+        assert a == b
+        return 'does_not_matter'
+
+    fuzz_lightyear.register_factory('nested')(nested_function)
+    fuzz_lightyear.register_factory('a')(child_a)
+    fuzz_lightyear.register_factory('b')(child_b)
+    fuzz_lightyear.register_factory('string')(function)
+
+    request = FuzzingRequest(
+        operation_id='get_expect_primitives',
+        tag='types',
+    )
+    request.send()
diff --git a/tests/unit/supplements/factory_supplements_test.py b/tests/unit/supplements/factory_supplements_test.py
index 4c0d3d7..08764fc 100644
--- a/tests/unit/supplements/factory_supplements_test.py
+++ b/tests/unit/supplements/factory_supplements_test.py
@@ -54,10 +54,6 @@ def setup(self):
     def test_uses_default(self):
         assert get_user_defined_mapping()['caller']() == 2
 
-    def test_uses_provided_value_over_default(self):
-        assert get_user_defined_mapping()['caller'](dependency=2) == 3
-        assert get_user_defined_mapping()['caller'](3) == 4
-
     def test_throws_error_when_no_default(self):
         def foobar(no_default):
             pass