diff --git a/jedi/api/__init__.py b/jedi/api/__init__.py
index bb017a0f..0a1b79cd 100644
--- a/jedi/api/__init__.py
+++ b/jedi/api/__init__.py
@@ -550,7 +550,9 @@ class Script(object):
 
         with common.scale_speed_settings(settings.scale_call_signatures):
             _callable = lambda: self._evaluator.eval_call(call)
-            origins = cache.cache_call_signatures(_callable, user_stmt)
+            origins = cache.cache_call_signatures(_callable, self.source,
+                                                  self._pos, user_stmt)
+            origins = self._evaluator.eval_call(call)
         debug.speed('func_call followed')
 
         return [classes.CallSignature(self._evaluator, o, call, index)
diff --git a/jedi/cache.py b/jedi/cache.py
index 6e5020de..d815f43a 100644
--- a/jedi/cache.py
+++ b/jedi/cache.py
@@ -21,6 +21,7 @@ import hashlib
 import gc
 import inspect
 import shutil
+import re
 try:
     import cPickle as pickle
 except ImportError:
@@ -96,9 +97,17 @@ def time_cache(time_add_setting):
 
 
 @time_cache("call_signatures_validity")
-def cache_call_signatures(stmt):
+def cache_call_signatures(source, user_pos, stmt):
+    """This function calculates the cache key."""
+    index = user_pos[0] - 1
+    lines = source.splitlines() or ['']
+    before_cursor = lines[index][:user_pos[1]]
+    other_lines = lines[stmt.start_pos[0]:index]
+    whole = '\n'.join(other_lines + [before_cursor])
+    before_bracket = re.match(r'.*\(', whole, re.DOTALL)
+
     module_path = stmt.get_parent_until().path
-    return None if module_path is None else (module_path, stmt.start_pos)
+    return None if module_path is None else (module_path, before_bracket, stmt.start_pos)
 
 
 def underscore_memoization(func):
diff --git a/test/test_cache.py b/test/test_cache.py
index 6ffe9e46..bbceb985 100644
--- a/test/test_cache.py
+++ b/test/test_cache.py
@@ -65,7 +65,7 @@ def test_modulepickling_delete_incompatible_cache():
 def test_star_import_cache_duration():
     new = 0.01
     old, jedi.settings.star_import_cache_validity = \
-            jedi.settings.star_import_cache_validity, new
+        jedi.settings.star_import_cache_validity, new
 
     cache._star_import_cache = {}  # first empty...
     # path needs to be not-None (otherwise caching effects are not visible)
@@ -78,3 +78,24 @@ def test_star_import_cache_duration():
     length = len(cache._star_import_cache)
     cache._star_import_cache = {}
     assert length == 1
+
+
+def test_cache_call_signatures():
+    """
+    See github issue #390.
+    """
+    def check(column, call_name, path=None):
+        assert jedi.Script(s, 1, column, path).call_signatures()[0].name == call_name
+
+    s = 'str(int())'
+
+    for i in range(3):
+        check(8, 'int')
+        check(4, 'str')
+        # Can keep doing these calls and always get the right result.
+
+    # Now lets specify a source_path of boo and alternate these calls, it
+    # should still work.
+    for i in range(3):
+        check(8, 'int', 'boo')
+        check(4, 'str', 'boo')