diff --git a/jedi/api/file_name.py b/jedi/api/file_name.py
index 5d680efb..fac187f6 100644
--- a/jedi/api/file_name.py
+++ b/jedi/api/file_name.py
@@ -20,7 +20,7 @@ def file_name_completions(evaluator, module_context, start_leaf, string, like_na
     must_start_with = os.path.basename(string) + like_name
     string = os.path.dirname(string)
 
-    string = _maybe_add_os_path_join(module_context, start_leaf, string)
+    string, is_in_os_path_join = _maybe_add_os_path_join(module_context, start_leaf, string)
     base_path = os.path.join(evaluator.project._path, string)
     try:
         listed = os.listdir(base_path)
@@ -29,7 +29,7 @@ def file_name_completions(evaluator, module_context, start_leaf, string, like_na
     for name in listed:
         if name.startswith(must_start_with):
             path_for_name = os.path.join(base_path, name)
-            if os.path.isdir(path_for_name):
+            if os.path.isdir(path_for_name) and not is_in_os_path_join:
                 name += os.path.sep
 
             yield classes.Completion(
@@ -97,8 +97,8 @@ def _maybe_add_os_path_join(module_context, start_leaf, string):
                 contexts = context.eval_node(atom)
                 if any([c.name.get_qualified_names(include_module_names=True)
                         != ('os', 'path', 'join') for c in contexts]):
-                    return string
+                    return string, False
                 nodes = arglist.children[:arglist.children.index(start_leaf):2]
-                return _add_strings(module_context, nodes, add_slash=True)
+                return _add_strings(module_context, nodes, add_slash=True), True
 
-    return string
+    return string, False
diff --git a/test/test_api/test_completion.py b/test/test_api/test_completion.py
index 8fb9538c..0ff73dc2 100644
--- a/test/test_api/test_completion.py
+++ b/test/test_api/test_completion.py
@@ -215,6 +215,7 @@ os_path = 'from os.path import *\n'
         (f2, os_path + 'join(dirname(__file__), "completion", "basi")', 43, ['c.py']),
         (f2, os_path + 'join(dirname(__file__), "completion", "basi)', 35, []),
         (f2, os_path + 'join(dirname(__file__), "completion", "basi)', 33, ['on']),
+        (f2, os_path + 'join(dirname(__file__), "completion", "basi")', 33, ['on']),
     ]
 )
 def test_file_path_completions(Script, file, code, column, expected):