diff --git a/jedi/parser/fast.py b/jedi/parser/fast.py
index 6cbf1737..1ce704ad 100644
--- a/jedi/parser/fast.py
+++ b/jedi/parser/fast.py
@@ -281,6 +281,8 @@ class FastParser(use_metaclass(CachedFastParser)):
 
         # Split only new lines. Distinction between \r\n is the tokenizer's
         # job.
+        # It seems like there's no problem with form feed characters here,
+        # because we're not counting lines.
         self._lines = source.splitlines(True)
         current_lines = []
         is_decorator = False
diff --git a/jedi/parser/user_context.py b/jedi/parser/user_context.py
index 0dc5edc0..3001e0af 100644
--- a/jedi/parser/user_context.py
+++ b/jedi/parser/user_context.py
@@ -56,7 +56,7 @@ class UserContext(object):
             else:
                 column = len(line) - tok_start_pos[1]
             # Multi-line docstrings must be accounted for.
-            first_line = (tok_str.splitlines() or [''])[0]
+            first_line = common.splitlines(tok_str)[0]
             column -= len(first_line)
             # Reverse the token again, so that it is in normal order again.
             yield typ, tok_str[::-1], (self._line_temp, column), prefix[::-1]
@@ -155,7 +155,8 @@ class UserContext(object):
         next_must_be_name = False
         next_is_key = False
         key_name = None
-        for tok_type, tok_str, start_pos, prefix in self._get_backwards_tokenizer(self.position):
+        generator = self._get_backwards_tokenizer(self.position)
+        for tok_type, tok_str, start_pos, prefix in generator:
             # TODO improve the speed by not tokenizing everything.
             #     def/class/import stops the process.
             if next_must_be_name:
@@ -181,6 +182,16 @@ class UserContext(object):
                 index += 1
             elif tok_str == '=':
                 next_is_key = True
+            elif tok_type == tokenize.ERRORTOKEN \
+                    and (tok_str.endswith('"') or tok_str.endswith("'")):
+                # -2, because we don't account for the newline in the beginning
+                # and want to remove the unfinished string literal.
+                end_pos = start_pos[0], start_pos[1] + len(tok_str) - 2
+                # Here we completely reset the for loop.
+                generator = self._get_backwards_tokenizer(end_pos)
+                level = 0
+                next_must_be_name = False
+                next_is_key = False
         return None, 0, None
 
     def get_context(self, yield_positions=False):
diff --git a/test/test_api/test_call_signatures.py b/test/test_api/test_call_signatures.py
index 815d7667..28546ecb 100644
--- a/test/test_api/test_call_signatures.py
+++ b/test/test_api/test_call_signatures.py
@@ -175,7 +175,13 @@ class TestCallSignatures(TestCase):
         self._run('str(";', 'str', 0)
 
     def test_whitespace_before_bracket(self):
+        self._run('str (', 'str', 0)
         self._run('str (";', 'str', 0)
+        self._run('str\n(', 'str', 0)
+
+    def test_brackets_in_string_literals(self):
+        self._run('str (" (', 'str', 0)
+        self._run('str (" )', 'str', 0)
 
 
 class TestParams(TestCase):