diff --git a/jedi/inference/finder.py b/jedi/inference/finder.py
index 1c8b02f6..18b02401 100644
--- a/jedi/inference/finder.py
+++ b/jedi/inference/finder.py
@@ -99,15 +99,17 @@ def _check_isinstance_type(value, node, search_name):
         args = TreeArguments(value.inference_state, value, arglist, trailer)
         param_list = list(args.unpack())
         # Disallow keyword arguments
-        if len(param_list) == 2:
-            (key1, lazy_value_object), (key2, lazy_value_cls) = param_list
+        if len(param_list) == 2 and len(arglist.children) == 3:
+            (key1, _), (key2, lazy_value_cls) = param_list
             if key1 is None and key2 is None:
-                call = helpers.call_of_leaf(search_name)
-                is_instance_call = helpers.call_of_leaf(lazy_value_object.data)
-                # Do a simple get_code comparison. They should just have the
-                # same code, and everything will be all right.
-                normalize = value.inference_state.grammar._normalize
-                if normalize(is_instance_call) == normalize(call):
+                call = _get_call_string(search_name)
+                is_instance_call = _get_call_string(arglist.children[0])
+                # Do a simple get_code comparison of the strings . They should
+                # just have the same code, and everything will be all right.
+                # There are ways that this is not correct, if some stuff is
+                # redefined in between. However here we don't care, because
+                # it's a heuristic that works pretty well.
+                if call == is_instance_call:
                     lazy_cls = lazy_value_cls
     if lazy_cls is None:
         return None
@@ -120,3 +122,16 @@ def _check_isinstance_type(value, node, search_name):
         else:
             value_set |= cls_or_tup.execute_with_values()
     return value_set
+
+
+def _get_call_string(node):
+    if node.parent.type == 'atom_expr':
+        return _get_call_string(node.parent)
+
+    code = ''
+    leaf = node.get_first_leaf()
+    end = node.get_last_leaf().end_pos
+    while leaf.start_pos < end:
+        code += leaf.value
+        leaf = leaf.get_next_leaf()
+    return code
diff --git a/jedi/inference/helpers.py b/jedi/inference/helpers.py
index 622f6051..3b0b33dd 100644
--- a/jedi/inference/helpers.py
+++ b/jedi/inference/helpers.py
@@ -110,49 +110,6 @@ def infer_call_of_leaf(context, leaf, cut_own_trailer=False):
     return values
 
 
-def call_of_leaf(leaf):
-    """
-    Creates a "call" node that consist of all ``trailer`` and ``power``
-    objects.  E.g. if you call it with ``append``::
-
-        list([]).append(3) or None
-
-    You would get a node with the content ``list([]).append`` back.
-
-    This generates a copy of the original ast node.
-
-    If you're using the leaf, e.g. the bracket `)` it will return ``list([])``.
-    """
-    # TODO this is the old version of this call. Try to remove it.
-    trailer = leaf.parent
-    # The leaf may not be the last or first child, because there exist three
-    # different trailers: `( x )`, `[ x ]` and `.x`. In the first two examples
-    # we should not match anything more than x.
-    if trailer.type != 'trailer' or leaf not in (trailer.children[0], trailer.children[-1]):
-        if trailer.type == 'atom':
-            return trailer
-        return leaf
-
-    power = trailer.parent
-    index = power.children.index(trailer)
-
-    new_power = copy.copy(power)
-    new_power.children = list(new_power.children)
-    new_power.children[index + 1:] = []
-
-    if power.type == 'error_node':
-        start = index
-        while True:
-            start -= 1
-            if power.children[start].type != 'trailer':
-                break
-        transformed = tree.Node('power', power.children[start:])
-        transformed.parent = power.parent
-        return transformed
-
-    return power
-
-
 def get_names_of_node(node):
     try:
         children = node.children
diff --git a/test/completion/isinstance.py b/test/completion/isinstance.py
index 15fb9a76..3eebfe27 100644
--- a/test/completion/isinstance.py
+++ b/test/completion/isinstance.py
@@ -99,3 +99,14 @@ class Test():
 
 #?
 isinstance(1, int())
+
+# -----------------
+# more complicated arguments
+# -----------------
+
+def ayyyyyye(obj):
+    if isinstance(obj.obj, str):
+        #?
+        obj.obj
+        #?
+        obj
diff --git a/test/test_inference/test_helpers.py b/test/test_inference/test_helpers.py
deleted file mode 100644
index 03a54eb8..00000000
--- a/test/test_inference/test_helpers.py
+++ /dev/null
@@ -1,15 +0,0 @@
-from textwrap import dedent
-
-from jedi.inference import helpers
-
-
-def test_call_of_leaf_in_brackets(Script):
-    s = dedent("""
-    x = 1
-    type(x)
-    """)
-    last_x = Script(s).names(references=True, definitions=False)[-1]
-    name = last_x._name.tree_name
-
-    call = helpers.call_of_leaf(name)
-    assert call == name