diff --git a/jedi/api/classes.py b/jedi/api/classes.py
index 83da30f0..82c28c5c 100644
--- a/jedi/api/classes.py
+++ b/jedi/api/classes.py
@@ -554,6 +554,8 @@ class CallDef(object):
             if isinstance(self._executable, er.InstanceElement):
                 return self._executable.params[1:]
             return self._executable.params
+        elif self._executable.isinstance(er.compiled.CompiledObject):
+            return self._executable.params
         else:
             try:
                 sub = self._executable.get_subscope_by_name('__init__')
diff --git a/jedi/evaluate/compiled/__init__.py b/jedi/evaluate/compiled/__init__.py
index 2c604e9f..a82fda7f 100644
--- a/jedi/evaluate/compiled/__init__.py
+++ b/jedi/evaluate/compiled/__init__.py
@@ -11,6 +11,9 @@ from jedi import debug
 from jedi.parser.representation import Base
 from jedi.cache import underscore_memoization
 from jedi.evaluate.sys_path import get_sys_path
+from jedi.parser.representation import Param
+from jedi.parser.representation import SubModule
+from jedi.evaluate.helpers import FakeName
 from . import fake
 
 
@@ -20,6 +23,20 @@ class CompiledObject(Base):
     asserts = []
     path = None  # modules have this attribute - set it to None.
 
+    @property
+    def params(self):
+        params_str, ret = self._parse_function_doc()
+        tokens = params_str.split(',')
+        params = []
+        module = SubModule(self.get_parent_until().name)
+        # it seems like start_pos/end_pos is always (0, 0) for a compiled
+        # object
+        start_pos, end_pos = (0, 0), (0, 0)
+        for p in tokens:
+            params.append(Param(module, [FakeName(p.strip())], start_pos,
+                                end_pos))
+        return params
+
     def __init__(self, obj, parent=None):
         self.obj = obj
         self.parent = parent
diff --git a/test/test_compiled.py b/test/test_compiled.py
index c783a3e2..1e9d03c1 100644
--- a/test/test_compiled.py
+++ b/test/test_compiled.py
@@ -10,10 +10,33 @@ from .helpers import cwd_at
 
 
 @cwd_at('test/extensions')
-def test_compiled():
+def test_completions():
     if platform.architecture()[0] == '64bit':
         package_name = "compiled%s%s" % sys.version_info[:2]
         sys.path.insert(0, os.getcwd())
         if os.path.exists(package_name):
             s = jedi.Script("from %s import compiled; compiled." % package_name)
             assert len(s.completions()) >= 2
+
+
+@cwd_at('test/extensions')
+def test_call_signatures_extension():
+    # with a cython extension
+    if platform.architecture()[0] == '64bit':
+        package_name = "compiled%s%s" % sys.version_info[:2]
+        sys.path.insert(0, os.getcwd())
+        if os.path.exists(package_name):
+            s = jedi.Script("from %s import compiled; compiled.Foo(" %
+                            package_name)
+            defs = s.call_signatures()
+            for call_def in defs:
+                for param in call_def.params:
+                    pass
+
+
+def test_call_signatures_stdlib():
+    code = "import math; math.cos("
+    s = jedi.Script(code)
+    defs = s.call_signatures()
+    for call_def in defs:
+        assert len(call_def.params) == 1