diff --git a/parso/python/tokenize.py b/parso/python/tokenize.py
index eda4c99..3dcb6c4 100644
--- a/parso/python/tokenize.py
+++ b/parso/python/tokenize.py
@@ -498,7 +498,7 @@ def tokenize_lines(lines, version_info, start_pos=(1, 0)):
                 pseudomatch = pseudo_token.match(line, pos)
             if not pseudomatch:  # scan for tokens
                 match = whitespace.match(line, pos)
-                if pos == 0:
+                if pos == 0 and paren_level == 0:
                     for t in dedent_if_necessary(match.end()):
                         yield t
                 pos = match.end()
diff --git a/test/test_diff_parser.py b/test/test_diff_parser.py
index 4f4bc1c..b7f5a5c 100644
--- a/test/test_diff_parser.py
+++ b/test/test_diff_parser.py
@@ -1007,7 +1007,7 @@ def test_random_unicode_characters(differ):
     differ.parse(s, parsers=1, expect_error_leaves=True)
     differ.parse('')
     differ.parse(s + '\n', parsers=1, expect_error_leaves=True)
-    differ.parse(u'   result = (\r\f\x17\t\x11res)', parsers=2, expect_error_leaves=True)
+    differ.parse(u'   result = (\r\f\x17\t\x11res)', parsers=1, expect_error_leaves=True)
     differ.parse('')
     differ.parse('   a( # xx\ndef', parsers=2, expect_error_leaves=True)
 
@@ -1124,7 +1124,7 @@ def test_all_sorts_of_indentation(differ):
                 end
         ''')
     differ.initialize(code1)
-    differ.parse(code2, copies=1, parsers=4, expect_error_leaves=True)
+    differ.parse(code2, copies=1, parsers=1, expect_error_leaves=True)
     differ.parse(code1, copies=1, parsers=3, expect_error_leaves=True)
 
     code3 = dedent('''\