diff --git a/RELEASE.rst b/RELEASE.rst
new file mode 100644
index 0000000000..52f5e7de30
--- /dev/null
+++ b/RELEASE.rst
@@ -0,0 +1,4 @@
+RELEASE_TYPE: patch
+
+This patch changes a few byte-string literals from double to single quotes,
+thanks to an update in :pypi:`unify`.  There are no user-visible changes.
diff --git a/requirements/tools.txt b/requirements/tools.txt
index 3c870060f1..9501aa6348 100644
--- a/requirements/tools.txt
+++ b/requirements/tools.txt
@@ -26,9 +26,9 @@ jinja2==2.10              # via pyupio, sphinx
 markupsafe==1.0           # via jinja2
 mccabe==0.6.1             # via flake8
 packaging==16.8           # via dparse, pyupio, safety
-pip-tools==1.10.1
+pip-tools==1.10.2
 pkginfo==1.4.1            # via twine
-pluggy==0.5.2             # via tox
+pluggy==0.6.0             # via tox
 py==1.5.2                 # via pytest, tox
 pycodestyle==2.3.1        # via autopep8, flake8
 pyflakes==1.6.0           # via autoflake, flake8
@@ -54,7 +54,7 @@ sphinxcontrib-websupport==1.0.1  # via sphinx
 tox==2.9.1
 tqdm==4.19.4              # via pyupio, twine
 twine==1.9.1
-unify==0.3                # via pyformat
+unify==0.4                # via pyformat
 untokenize==0.1.1         # via docformatter, unify
 urllib3==1.22             # via requests
 virtualenv==15.1.0        # via tox
diff --git a/scripts/hypothesistooling.py b/scripts/hypothesistooling.py
index 57dd7ab5b7..9462bb301d 100644
--- a/scripts/hypothesistooling.py
+++ b/scripts/hypothesistooling.py
@@ -33,7 +33,7 @@ def current_branch():
 def tags():
     result = [t.decode('ascii') for t in subprocess.check_output([
         'git', 'tag'
-    ]).split(b"\n")]
+    ]).split(b'\n')]
     assert len(set(result)) == len(result)
     return set(result)
 
@@ -194,7 +194,7 @@ def modified_files():
         for l in diff_output.split('\n'):
             filepath = l.strip()
             if filepath:
-                assert os.path.exists(filepath)
+                assert os.path.exists(filepath), filepath
                 files.add(filepath)
     return files
 
diff --git a/src/hypothesis/internal/conjecture/engine.py b/src/hypothesis/internal/conjecture/engine.py
index 84ac998224..c8eddb78b7 100644
--- a/src/hypothesis/internal/conjecture/engine.py
+++ b/src/hypothesis/internal/conjecture/engine.py
@@ -368,11 +368,11 @@ def downgrade_buffer(self, buffer):
 
     @property
     def secondary_key(self):
-        return b'.'.join((self.database_key, b"secondary"))
+        return b'.'.join((self.database_key, b'secondary'))
 
     @property
     def covering_key(self):
-        return b'.'.join((self.database_key, b"coverage"))
+        return b'.'.join((self.database_key, b'coverage'))
 
     def note_details(self, data):
         if data.status == Status.INTERESTING:
diff --git a/tests/cover/test_database_backend.py b/tests/cover/test_database_backend.py
index 28130a528b..2227f8f4a2 100644
--- a/tests/cover/test_database_backend.py
+++ b/tests/cover/test_database_backend.py
@@ -113,14 +113,14 @@ def test_selects_sqlite_database_if_name_matches(tmpdir):
 
 def test_selects_directory_based_if_already_directory(tmpdir):
     path = str(tmpdir.join('hi.sqlite3'))
-    DirectoryBasedExampleDatabase(path).save(b"foo", b"bar")
+    DirectoryBasedExampleDatabase(path).save(b'foo', b'bar')
     assert isinstance(ExampleDatabase(path), DirectoryBasedExampleDatabase)
 
 
 @checks_deprecated_behaviour
 def test_selects_sqlite_if_already_sqlite(tmpdir):
     path = str(tmpdir.join('hi'))
-    SQLiteExampleDatabase(path).save(b"foo", b"bar")
+    SQLiteExampleDatabase(path).save(b'foo', b'bar')
     assert isinstance(ExampleDatabase(path), SQLiteExampleDatabase)
 
 
@@ -169,13 +169,13 @@ def test_class_name_is_in_repr(exampledatabase):
 
 
 def test_an_absent_value_is_present_after_it_moves(exampledatabase):
-    exampledatabase.move(b"a", b"b", b"c")
-    assert next(exampledatabase.fetch(b"b")) == b'c'
+    exampledatabase.move(b'a', b'b', b'c')
+    assert next(exampledatabase.fetch(b'b')) == b'c'
 
 
 def test_an_absent_value_is_present_after_it_moves_to_self(exampledatabase):
-    exampledatabase.move(b"a", b"a", b"b")
-    assert next(exampledatabase.fetch(b"a")) == b'b'
+    exampledatabase.move(b'a', b'a', b'b')
+    assert next(exampledatabase.fetch(b'a')) == b'b'
 
 
 def test_two_directory_databases_can_interact(tmpdir):
diff --git a/tests/cover/test_database_usage.py b/tests/cover/test_database_usage.py
index 26cfbea348..cc33f75c20 100644
--- a/tests/cover/test_database_usage.py
+++ b/tests/cover/test_database_usage.py
@@ -32,7 +32,7 @@ def has_a_non_zero_byte(x):
 
 
 def test_saves_incremental_steps_in_database():
-    key = b"a database key"
+    key = b'a database key'
     database = InMemoryExampleDatabase()
     find(
         st.binary(min_size=10), lambda x: has_a_non_zero_byte(x),
@@ -42,7 +42,7 @@ def test_saves_incremental_steps_in_database():
 
 
 def test_clears_out_database_as_things_get_boring():
-    key = b"a database key"
+    key = b'a database key'
     database = InMemoryExampleDatabase()
     do_we_care = True
 
@@ -73,7 +73,7 @@ def stuff():
 
 
 def test_trashes_invalid_examples():
-    key = b"a database key"
+    key = b'a database key'
     database = InMemoryExampleDatabase()
     finicky = False
 
@@ -96,7 +96,7 @@ def stuff():
 
 
 def test_respects_max_examples_in_database_usage():
-    key = b"a database key"
+    key = b'a database key'
     database = InMemoryExampleDatabase()
     do_we_care = True
     counter = [0]