diff --git a/jedi/api/__init__.py b/jedi/api/__init__.py
index f521fc7c..faea9d02 100644
--- a/jedi/api/__init__.py
+++ b/jedi/api/__init__.py
@@ -15,7 +15,7 @@ import sys
 from itertools import chain
 
 from jedi._compatibility import next, unicode, builtins
-from jedi.parser import Parser
+from jedi.parser import Parser, load_grammar
 from jedi.parser.tokenize import source_tokens
 from jedi.parser import tree as pr
 from jedi.parser.user_context import UserContext, UserContextParser
@@ -100,9 +100,11 @@ class Script(object):
 
         cache.clear_time_caches()
         debug.reset_time()
+        self._grammar = load_grammar('grammar3.4')
         self._user_context = UserContext(self.source, self._pos)
-        self._parser = UserContextParser(self.source, path, self._pos, self._user_context)
-        self._evaluator = Evaluator()
+        self._parser = UserContextParser(self._grammar, self.source, path,
+                                         self._pos, self._user_context)
+        self._evaluator = Evaluator(self._grammar)
         debug.speed('init')
 
     @property
@@ -277,7 +279,7 @@ class Script(object):
 
     def _get_under_cursor_stmt(self, cursor_txt):
         tokenizer = source_tokens(cursor_txt, line_offset=self._pos[0] - 1)
-        r = Parser(cursor_txt, no_docstr=True, tokenizer=tokenizer)
+        r = Parser(self._grammar, cursor_txt, tokenizer=tokenizer)
         try:
             # Take the last statement available.
             stmt = r.module.statements[-1]
@@ -674,11 +676,10 @@ def defined_names(source, path=None, encoding='utf-8'):
 
     :rtype: list of classes.Definition
     """
-    parser = Parser(
-        common.source_to_unicode(source, encoding),
-        module_path=path,
-    )
-    return classes.defined_names(Evaluator(), parser.module)
+    grammar = load_grammar('grammar3.4')
+    parser = Parser(grammar, common.source_to_unicode(source, encoding),
+                    module_path=path)
+    return classes.defined_names(Evaluator(grammar), parser.module)
 
 
 def names(source=None, path=None, encoding='utf-8', all_scopes=False,
diff --git a/jedi/api/usages.py b/jedi/api/usages.py
index c40f81cd..434d4bfb 100644
--- a/jedi/api/usages.py
+++ b/jedi/api/usages.py
@@ -60,7 +60,7 @@ def usages(evaluator, definition_names, mods):
     compare_definitions = compare_array(definition_names)
     mods |= set([d.get_parent_until() for d in definition_names])
     definitions = []
-    for m in imports.get_modules_containing_name(mods, search_name):
+    for m in imports.get_modules_containing_name(evaluator, mods, search_name):
         try:
             check_names = m.used_names[search_name]
         except KeyError:
diff --git a/jedi/evaluate/__init__.py b/jedi/evaluate/__init__.py
index 9bf8842a..2f2dd334 100644
--- a/jedi/evaluate/__init__.py
+++ b/jedi/evaluate/__init__.py
@@ -91,7 +91,8 @@ from jedi.evaluate.helpers import FakeStatement, deep_ast_copy, call_of_name
 
 
 class Evaluator(object):
-    def __init__(self):
+    def __init__(self, grammar):
+        self._grammar = grammar
         self.memoize_cache = {}  # for memoize decorators
         self.import_cache = {}  # like `sys.modules`.
         self.compiled_cache = {}  # see `compiled.create()`
diff --git a/jedi/evaluate/compiled/fake.py b/jedi/evaluate/compiled/fake.py
index 4e1f5fe8..e0028c81 100644
--- a/jedi/evaluate/compiled/fake.py
+++ b/jedi/evaluate/compiled/fake.py
@@ -8,8 +8,7 @@ import os
 import inspect
 
 from jedi._compatibility import is_py3, builtins, unicode
-from jedi.parser import Parser
-from jedi.parser import tokenize
+from jedi.parser import Parser, load_grammar
 from jedi.parser.tree import Class
 from jedi.evaluate.helpers import FakeName
 
@@ -31,7 +30,8 @@ def _load_faked_module(module):
         except IOError:
             modules[module_name] = None
             return
-        module = Parser(unicode(source), module_name).module
+        grammar = load_grammar('grammar3.4')
+        module = Parser(grammar, unicode(source), module_name).module
         modules[module_name] = module
 
         if module_name == 'builtins' and not is_py3:
diff --git a/jedi/evaluate/docstrings.py b/jedi/evaluate/docstrings.py
index 78e9d885..b930c6d3 100644
--- a/jedi/evaluate/docstrings.py
+++ b/jedi/evaluate/docstrings.py
@@ -127,7 +127,7 @@ def _evaluate_for_statement_string(evaluator, string, module):
         # (e.g., 'threading' in 'threading.Thread').
         string = 'import %s\n' % element + string
 
-    p = Parser(code % indent_block(string), no_docstr=True)
+    p = Parser(evaluator.grammar, code % indent_block(string), no_docstr=True)
     pseudo_cls = p.module.subscopes[0]
     try:
         stmt = pseudo_cls.statements[-1]
diff --git a/jedi/evaluate/dynamic.py b/jedi/evaluate/dynamic.py
index 6b25769e..cfd7c2d9 100644
--- a/jedi/evaluate/dynamic.py
+++ b/jedi/evaluate/dynamic.py
@@ -174,7 +174,7 @@ def search_params(evaluator, param):
     try:
         result = []
         # This is like backtracking: Get the first possible result.
-        for mod in imports.get_modules_containing_name([current_module], func_name):
+        for mod in imports.get_modules_containing_name(evaluator, [current_module], func_name):
             result = get_params_for_module(mod)
             if result:
                 break
diff --git a/jedi/evaluate/finder.py b/jedi/evaluate/finder.py
index d1b700b6..d755cbe0 100644
--- a/jedi/evaluate/finder.py
+++ b/jedi/evaluate/finder.py
@@ -492,8 +492,8 @@ def get_names_of_scope(evaluator, scope, position=None, star_search=True, includ
     the current scope is function:
 
     >>> from jedi._compatibility import u
-    >>> from jedi.parser import Parser
-    >>> parser = Parser(u('''
+    >>> from jedi.parser import Parser, load_grammar
+    >>> parser = Parser(load_grammar('python3.4'), u('''
     ... x = ['a', 'b', 'c']
     ... def func():
     ...     y = None
diff --git a/jedi/evaluate/imports.py b/jedi/evaluate/imports.py
index bca8aa32..9e1e15d4 100644
--- a/jedi/evaluate/imports.py
+++ b/jedi/evaluate/imports.py
@@ -184,7 +184,7 @@ class ImportWrapper2(pr.Base):
                         rel_path = os.path.join(self._importer.get_relative_path(),
                                                 '__init__.py')
                         if os.path.exists(rel_path):
-                            m = _load_module(rel_path)
+                            m = _load_module(self.evaluator, rel_path)
                             names += m.get_defined_names()
             else:
                 # flask
@@ -590,9 +590,9 @@ class _Importer(object):
             else:
                 source = current_namespace[0].read()
                 current_namespace[0].close()
-            return _load_module(path, source, sys_path=sys_path), rest
+            return _load_module(self.evaluator, path, source, sys_path=sys_path), rest
         else:
-            return _load_module(name=path, sys_path=sys_path), rest
+            return _load_module(self.evaluator, name=path, sys_path=sys_path), rest
 
 
 def follow_imports(evaluator, scopes):
@@ -633,7 +633,7 @@ def remove_star_imports(evaluator, scope, ignored_modules=()):
     return set(modules)
 
 
-def _load_module(path=None, source=None, name=None, sys_path=None):
+def _load_module(evaluator, path=None, source=None, name=None, sys_path=None):
     def load(source):
         dotted_path = path and compiled.dotted_from_fs_path(path, sys_path)
         if path is not None and path.endswith('.py') \
@@ -644,7 +644,7 @@ def _load_module(path=None, source=None, name=None, sys_path=None):
         else:
             return compiled.load_module(path, name)
         p = path or name
-        p = fast.FastParser(common.source_to_unicode(source), p)
+        p = fast.FastParser(evaluator.grammar, common.source_to_unicode(source), p)
         cache.save_parser(path, name, p)
         return p.module
 
@@ -652,7 +652,7 @@ def _load_module(path=None, source=None, name=None, sys_path=None):
     return load(source) if cached is None else cached.module
 
 
-def get_modules_containing_name(mods, name):
+def get_modules_containing_name(evaluator, mods, name):
     """
     Search a name in the directories of modules.
     """
@@ -669,7 +669,7 @@ def get_modules_containing_name(mods, name):
         with open(path, 'rb') as f:
             source = source_to_unicode(f.read())
             if name in source:
-                return _load_module(path, source)
+                return _load_module(evaluator, path, source)
 
     # skip non python modules
     mods = set(m for m in mods if not isinstance(m, compiled.CompiledObject))
diff --git a/jedi/evaluate/stdlib.py b/jedi/evaluate/stdlib.py
index 1e29e587..c9e285e3 100644
--- a/jedi/evaluate/stdlib.py
+++ b/jedi/evaluate/stdlib.py
@@ -227,7 +227,7 @@ def collections_namedtuple(evaluator, obj, params):
     )
 
     # Parse source
-    generated_class = Parser(unicode(source)).module.subscopes[0]
+    generated_class = Parser(evaluator.grammar, unicode(source)).module.subscopes[0]
     return [er.Class(evaluator, generated_class)]
 
 
diff --git a/jedi/evaluate/sys_path.py b/jedi/evaluate/sys_path.py
index 5c85890d..0d7bd670 100644
--- a/jedi/evaluate/sys_path.py
+++ b/jedi/evaluate/sys_path.py
@@ -140,7 +140,7 @@ def sys_path_with_modifications(evaluator, module):
         except IOError:
             pass
         else:
-            p = Parser(common.source_to_unicode(source), module_path)
+            p = Parser(evaluator.grammar, common.source_to_unicode(source), module_path)
             for path in _check_module(p.module):
                 if path not in buildout_paths:
                     buildout_paths.add(path)
diff --git a/jedi/parser/__init__.py b/jedi/parser/__init__.py
index a1935ca9..6e665cde 100644
--- a/jedi/parser/__init__.py
+++ b/jedi/parser/__init__.py
@@ -15,16 +15,14 @@ within the statement. This lowers memory usage and cpu time and reduces the
 complexity of the ``Parser`` (there's another parser sitting inside
 ``Statement``, which produces ``Array`` and ``Call``).
 """
-import keyword
 import logging
+import os
 
-from jedi._compatibility import next, unicode
-from jedi import debug
+from jedi._compatibility import next
 from jedi import common
 from jedi.parser import tree as pt
 from jedi.parser import tokenize
 from jedi.parser import pytree
-from jedi.parser.pgen2 import Driver
 from jedi.parser import pgen2
 
 OPERATOR_KEYWORDS = 'and', 'for', 'if', 'else', 'in', 'is', 'lambda', 'not', 'or'
@@ -33,20 +31,33 @@ STATEMENT_KEYWORDS = 'assert', 'del', 'global', 'nonlocal', 'raise', \
     'return', 'yield', 'pass', 'continue', 'break'
 
 
+_loaded_grammars = {}
+
+
+def load_grammar(file):
+    global _loaded_grammars
+    path = os.path.join(os.path.dirname(__file__), file) + '.txt'
+    try:
+        return _loaded_grammars[path]
+    except KeyError:
+        return _loaded_grammars.setdefault(path, pgen2.load_grammar(path))
+
+
 class Parser(object):
     """
     This class is used to parse a Python file, it then divides them into a
     class structure of different scopes.
 
-    :param source: The codebase for the parser.
-    :type source: str
+    :param grammar: The grammar object of pgen2. Loaded by load_grammar.
+    :param source: The codebase for the parser. Must be unicode.
     :param module_path: The path of the module in the file system, may be None.
     :type module_path: str
-    :param no_docstr: If True, a string at the beginning is not a docstr.
     :param top_module: Use this module as a parent instead of `self.module`.
     """
-    def __init__(self, source, module_path=None, no_docstr=False,
-                 tokenizer=None, top_module=None):
+    def __init__(self, grammar, source, module_path=None, tokenizer=None):
+        """
+        This is the way I imagine a parser describing the init function
+        """
 
         if not source.endswith('\n'):
             source += '\n'
@@ -90,8 +101,8 @@ class Parser(object):
         self.used_names = {}
         self.scope_names_stack = [{}]
         logger = logging.getLogger("Jedi-Parser")
-        d = Driver(pytree.python_grammar, self.convert_node, self.convert_leaf,
-                   self.error_recovery, logger=logger)
+        d = pgen2.Driver(grammar, self.convert_node,
+                         self.convert_leaf, self.error_recovery, logger=logger)
         self.module = d.parse_string(source).get_parent_until()
 
         self.module.used_names = self.used_names
diff --git a/jedi/parser/fast.py b/jedi/parser/fast.py
index 4ab26b8e..7c5877fb 100644
--- a/jedi/parser/fast.py
+++ b/jedi/parser/fast.py
@@ -56,13 +56,13 @@ class Module(pr.Module, pr.Simple):
 
 class CachedFastParser(type):
     """ This is a metaclass for caching `FastParser`. """
-    def __call__(self, source, module_path=None):
+    def __call__(self, grammar, source, module_path=None):
         if not settings.fast_parser:
-            return Parser(source, module_path)
+            return Parser(grammar, source, module_path)
 
         pi = cache.parser_cache.get(module_path, None)
         if pi is None or isinstance(pi.parser, Parser):
-            p = super(CachedFastParser, self).__call__(source, module_path)
+            p = super(CachedFastParser, self).__call__(grammar, source, module_path)
         else:
             p = pi.parser  # pi is a `cache.ParserCacheItem`
             p.update(source)
@@ -186,8 +186,9 @@ class FastParser(use_metaclass(CachedFastParser)):
 
     _keyword_re = re.compile('^[ \t]*(def|class|@|%s)' % '|'.join(tokenize.FLOWS))
 
-    def __init__(self, code, module_path=None):
+    def __init__(self, grammar, code, module_path=None):
         # set values like `pr.Module`.
+        self._grammar = grammar
         self.module_path = module_path
 
         self.current_node = None
diff --git a/jedi/parser/pytree.py b/jedi/parser/pytree.py
index 3acfe018..3fe39509 100644
--- a/jedi/parser/pytree.py
+++ b/jedi/parser/pytree.py
@@ -18,6 +18,7 @@ from . import pgen2
 
 # The grammar file
 _GRAMMAR_FILE = os.path.join(os.path.dirname(__file__), "grammar3.4.txt")
+python_grammar = pgen2.load_grammar(_GRAMMAR_FILE)
 
 
 class Symbols(object):
diff --git a/jedi/parser/user_context.py b/jedi/parser/user_context.py
index 53c67de2..387eb50c 100644
--- a/jedi/parser/user_context.py
+++ b/jedi/parser/user_context.py
@@ -202,7 +202,8 @@ class UserContext(object):
 
 
 class UserContextParser(object):
-    def __init__(self, source, path, position, user_context):
+    def __init__(self, grammar, source, path, position, user_context):
+        self._grammar = grammar
         self._source = source
         self._path = path and os.path.abspath(path)
         self._position = position
@@ -211,7 +212,7 @@ class UserContextParser(object):
     @cache.underscore_memoization
     def _parser(self):
         cache.invalidate_star_import_cache(self._path)
-        parser = FastParser(self._source, self._path)
+        parser = FastParser(self._grammar, self._source, self._path)
         # Don't pickle that module, because the main module is changing quickly
         cache.save_parser(self._path, None, parser, pickling=False)
         return parser