diff --git a/jedi/evaluate/__init__.py b/jedi/evaluate/__init__.py
index c5c6a78a..3b6992ed 100644
--- a/jedi/evaluate/__init__.py
+++ b/jedi/evaluate/__init__.py
@@ -164,7 +164,7 @@ class Evaluator(object):
                 name, position=stmt.start_pos, search_global=True)
 
             for_stmt = tree.search_ancestor(stmt, 'for_stmt')
-            if isinstance(for_stmt, tree.ForStmt) and types \
+            if for_stmt is not None and for_stmt.type == 'for_stmt' and types \
                     and for_stmt.defines_one_name():
                 # Iterate through result and add the values, that's possible
                 # only in for loops without clutter, because they are
@@ -271,18 +271,19 @@ class Evaluator(object):
     def _eval_element_not_cached(self, context, element):
         debug.dbg('eval_element %s@%s', element, element.start_pos)
         types = set()
-        if isinstance(element, (tree.Name, tree.Literal)) or element.type == 'atom':
+        typ = element.type
+        if isinstance(element, (tree.Name, tree.Literal)) or typ == 'atom':
             types = self.eval_atom(context, element)
-        elif isinstance(element, tree.Keyword):
+        elif typ == 'keyword':
             # For False/True/None
             if element.value in ('False', 'True', 'None'):
                 types.add(compiled.builtin_from_name(self, element.value))
             # else: print e.g. could be evaluated like this in Python 2.7
-        elif isinstance(element, tree.Lambda):
+        elif typ == 'lambda':
             types = set([er.FunctionContext(self, context, element)])
-        elif element.type == 'expr_stmt':
+        elif typ == 'expr_stmt':
             types = self.eval_statement(context, element)
-        elif element.type in ('power', 'atom_expr'):
+        elif typ in ('power', 'atom_expr'):
             first_child = element.children[0]
             if not (first_child.type == 'keyword' and first_child.value == 'await'):
                 types = self.eval_atom(context, first_child)
@@ -292,22 +293,22 @@ class Evaluator(object):
                         types = set(precedence.calculate(self, context, types, trailer, right))
                         break
                     types = self.eval_trailer(context, types, trailer)
-        elif element.type in ('testlist_star_expr', 'testlist',):
+        elif typ in ('testlist_star_expr', 'testlist',):
             # The implicit tuple in statements.
             types = set([iterable.SequenceLiteralContext(self, context, element)])
-        elif element.type in ('not_test', 'factor'):
+        elif typ in ('not_test', 'factor'):
             types = self.eval_element(context, element.children[-1])
             for operator in element.children[:-1]:
                 types = set(precedence.factor_calculate(self, types, operator))
-        elif element.type == 'test':
+        elif typ == 'test':
             # `x if foo else y` case.
             types = (self.eval_element(context, element.children[0]) |
                      self.eval_element(context, element.children[-1]))
-        elif element.type == 'operator':
+        elif typ == 'operator':
             # Must be an ellipsis, other operators are not evaluated.
             assert element.value == '...'
             types = set([compiled.create(self, Ellipsis)])
-        elif element.type == 'dotted_name':
+        elif typ == 'dotted_name':
             types = self.eval_atom(context, element.children[0])
             for next_name in element.children[2::2]:
                 # TODO add search_global=True?
@@ -316,9 +317,9 @@ class Evaluator(object):
                     for typ in types
                 )
             types = types
-        elif element.type == 'eval_input':
+        elif typ == 'eval_input':
             types = self._eval_element_not_cached(context, element.children[0])
-        elif element.type == 'annassign':
+        elif typ == 'annassign':
             print(element.children[1])
             types = pep0484._evaluate_for_annotation(context, element.children[1])
             print('xxx')
@@ -333,10 +334,10 @@ class Evaluator(object):
         generate the node (because it has just one child). In that case an atom
         might be a name or a literal as well.
         """
-        if isinstance(atom, tree.Name):
+        if atom.type == 'name':
             # This is the first global lookup.
             stmt = atom.get_definition()
-            if isinstance(stmt, tree.CompFor):
+            if stmt.type == 'comp_for':
                 stmt = tree.search_ancestor(stmt, ('expr_stmt', 'lambda', 'funcdef', 'classdef'))
             if stmt is None or stmt.type != 'expr_stmt':
                 # We only need to adjust the start_pos for statements, because
@@ -490,7 +491,7 @@ class Evaluator(object):
                             if param_name.string_name == name.value:
                                 param_names.append(param_name)
                 return param_names
-        elif isinstance(par, tree.ExprStmt) and name in par.get_defined_names():
+        elif par.type == 'expr_stmt' and name in par.get_defined_names():
             # Only take the parent, because if it's more complicated than just
             # a name it's something you can "goto" again.
             return [TreeNameDefinition(context, name)]