diff --git a/jedi/evaluate/imports.py b/jedi/evaluate/imports.py
index 3a1d93af..a985fde0 100644
--- a/jedi/evaluate/imports.py
+++ b/jedi/evaluate/imports.py
@@ -252,10 +252,8 @@ class Importer(object):
 
     def sys_path_with_modifications(self):
         in_path = []
-        sys_path_mod = list(sys_path.sys_path_with_modifications(
-            self._evaluator,
-            self.module_context
-        ))
+        sys_path_mod = self._evaluator.project.sys_path \
+                       + sys_path.check_sys_path_modifications(self.module_context)
         if self.file_path is not None:
             # If you edit e.g. gunicorn, there will be imports like this:
             # `from gunicorn import something`. But gunicorn is not in the
diff --git a/jedi/evaluate/project.py b/jedi/evaluate/project.py
index fbb0b59d..b90f0f0c 100644
--- a/jedi/evaluate/project.py
+++ b/jedi/evaluate/project.py
@@ -7,10 +7,12 @@ from jedi.cache import underscore_memoization
 
 class Project(object):
     def __init__(self, sys_path=None):
-        if sys_path is None:
-            venv = os.getenv('VIRTUAL_ENV')
-            if venv:
-                sys_path = get_venv_path(venv)
+        if sys_path is not None:
+            self._sys_path = sys_path
+
+        venv = os.getenv('VIRTUAL_ENV')
+        if venv:
+            sys_path = get_venv_path(venv)
 
         if sys_path is None:
             sys_path = sys.path
diff --git a/jedi/evaluate/sys_path.py b/jedi/evaluate/sys_path.py
index dee78677..d3a65638 100644
--- a/jedi/evaluate/sys_path.py
+++ b/jedi/evaluate/sys_path.py
@@ -5,7 +5,7 @@ import imp
 from jedi.evaluate.site import addsitedir
 
 from jedi._compatibility import unicode
-from jedi.evaluate.cache import evaluator_function_cache
+from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate.base_context import ContextualizedNode
 from jedi.evaluate.helpers import is_string
 from jedi import settings
@@ -150,6 +150,7 @@ def _paths_from_list_modifications(module_context, trailer1, trailer2):
                 yield abs_path
 
 
+@evaluator_method_cache(default=[])
 def check_sys_path_modifications(module_context):
     """
     Detect sys.path modifications within module.
@@ -187,7 +188,6 @@ def check_sys_path_modifications(module_context):
     return added
 
 
-@evaluator_function_cache(default=[])
 def sys_path_with_modifications(evaluator, module_context):
     return evaluator.project.sys_path + check_sys_path_modifications(module_context)