diff --git a/jedi/api/__init__.py b/jedi/api/__init__.py
index de4fa3e6..1dae24b9 100644
--- a/jedi/api/__init__.py
+++ b/jedi/api/__init__.py
@@ -15,7 +15,7 @@ import sys
 
 import parso
 from parso.python import tree
-from parso.utils import source_to_unicode, splitlines
+from parso.utils import source_to_unicode, split_lines
 
 from jedi.parser_utils import get_executable_nodes, get_statement_of_position
 from jedi import debug
@@ -109,8 +109,9 @@ class Script(object):
             with open(path, 'rb') as f:
                 source = f.read()
 
-        self._source = source_to_unicode(source, encoding)
-        self._code_lines = splitlines(self._source)
+        # TODO do we really want that?
+        self._source = source_to_unicode(source, encoding, errors='replace')
+        self._code_lines = split_lines(self._source)
         line = max(len(self._code_lines), 1) if line is None else line
         if not (0 < line <= len(self._code_lines)):
             raise ValueError('`line` parameter is not in a valid range.')
diff --git a/jedi/api/helpers.py b/jedi/api/helpers.py
index 34f76daa..09659f56 100644
--- a/jedi/api/helpers.py
+++ b/jedi/api/helpers.py
@@ -7,7 +7,7 @@ from textwrap import dedent
 
 from parso.python.parser import Parser
 from parso.python import tree
-from parso.utils import splitlines
+from parso.utils import split_lines
 
 from jedi._compatibility import u
 from jedi.evaluate.helpers import evaluate_call_of_leaf
@@ -53,7 +53,7 @@ class OnErrorLeaf(Exception):
 
 
 def _is_on_comment(leaf, position):
-    comment_lines = splitlines(leaf.prefix)
+    comment_lines = split_lines(leaf.prefix)
     difference = leaf.start_pos[0] - position[0]
     prefix_start_pos = leaf.get_start_pos_of_prefix()
     if difference == 0:
diff --git a/jedi/evaluate/imports.py b/jedi/evaluate/imports.py
index ebe61106..3fc713f0 100644
--- a/jedi/evaluate/imports.py
+++ b/jedi/evaluate/imports.py
@@ -510,7 +510,7 @@ def get_modules_containing_name(evaluator, modules, name):
 
     def check_fs(path):
         with open(path, 'rb') as f:
-            code = source_to_unicode(f.read())
+            code = source_to_unicode(f.read(), errors='replace')
             if name in code:
                 module_name = os.path.basename(path)[:-3]  # Remove `.py`.
                 module = _load_module(evaluator, path, code)
diff --git a/jedi/evaluate/representation.py b/jedi/evaluate/representation.py
index 80697806..68902604 100644
--- a/jedi/evaluate/representation.py
+++ b/jedi/evaluate/representation.py
@@ -548,7 +548,7 @@ class ModuleContext(use_metaclass(CachedMetaClass, context.TreeContext)):
         init_path = self.py__file__()
         if os.path.basename(init_path) == '__init__.py':
             with open(init_path, 'rb') as f:
-                content = source_to_unicode(f.read())
+                content = source_to_unicode(f.read(), errors='replace')
                 # these are strings that need to be used for namespace packages,
                 # the first one is ``pkgutil``, the second ``pkg_resources``.
                 options = ('declare_namespace(__name__)', 'extend_path(__path__')
diff --git a/jedi/refactoring.py b/jedi/refactoring.py
index e81b0040..51bdd683 100644
--- a/jedi/refactoring.py
+++ b/jedi/refactoring.py
@@ -15,7 +15,7 @@ following functions (sometimes bug-prone):
 import difflib
 
 from jedi import common
-from parso.utils import source_to_unicode, splitlines
+from parso.utils import source_to_unicode, split_lines
 from jedi.evaluate import helpers
 
 
@@ -83,7 +83,7 @@ def _rename(names, replace_str):
                 with open(current_path) as f:
                     source = f.read()
 
-            new_lines = splitlines(source_to_unicode(source))
+            new_lines = split_lines(source_to_unicode(source))
             old_lines = new_lines[:]
 
         nr, indent = name.line, name.column
@@ -101,7 +101,7 @@ def extract(script, new_name):
     :type source: str
     :return: list of changed lines/changed files
     """
-    new_lines = splitlines(source_to_unicode(script.source))
+    new_lines = split_lines(source_to_unicode(script.source))
     old_lines = new_lines[:]
 
     user_stmt = script._parser.user_stmt()
@@ -160,7 +160,7 @@ def inline(script):
     """
     :type script: api.Script
     """
-    new_lines = splitlines(source_to_unicode(script.source))
+    new_lines = split_lines(source_to_unicode(script.source))
 
     dct = {}
 
diff --git a/jedi/utils.py b/jedi/utils.py
index 655dc1ba..40cfca0d 100644
--- a/jedi/utils.py
+++ b/jedi/utils.py
@@ -11,7 +11,7 @@ import re
 import os
 import sys
 
-from parso.utils import splitlines
+from parso.utils import split_lines
 
 from jedi import Interpreter
 from jedi.api.helpers import get_on_completion_name
@@ -86,7 +86,7 @@ def setup_readline(namespace_module=__main__):
                     logging.debug("Start REPL completion: " + repr(text))
                     interpreter = Interpreter(text, [namespace_module.__dict__])
 
-                    lines = splitlines(text)
+                    lines = split_lines(text)
                     position = (len(lines), len(lines[-1]))
                     name = get_on_completion_name(
                         interpreter._get_module_node(),