diff --git a/.drone.yml b/.drone.yml
index 73164af..27243e2 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -28,6 +28,12 @@ steps:
   - pip install codecov
   - codecov
 
+- name: linting
+  image: python:3.6
+  commands:
+  - pip install flake8
+  - flake8
+
 ---
 kind: pipeline
 name: publish
diff --git a/src/humulus/__init__.py b/src/humulus/__init__.py
index c88f342..5af77a7 100644
--- a/src/humulus/__init__.py
+++ b/src/humulus/__init__.py
@@ -13,3 +13,5 @@
 # limitations under the License.
 
 from humulus.app import create_app
+
+__all__ = ['create_app', ]
diff --git a/src/humulus/app.py b/src/humulus/app.py
index 0e078b0..19a8319 100644
--- a/src/humulus/app.py
+++ b/src/humulus/app.py
@@ -14,8 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import os
-
 from flask import Flask, render_template
 
 
diff --git a/src/humulus/couch.py b/src/humulus/couch.py
index 6fd1da1..114bafb 100644
--- a/src/humulus/couch.py
+++ b/src/humulus/couch.py
@@ -26,6 +26,7 @@ from flask import abort, current_app, g
 from flask.cli import with_appcontext
 from slugify import slugify
 
+
 def get_couch():
     """Connect to the configured CouchDB."""
     if 'couch' not in g:
diff --git a/src/humulus/filters.py b/src/humulus/filters.py
index 8064afb..e0b4b79 100644
--- a/src/humulus/filters.py
+++ b/src/humulus/filters.py
@@ -59,7 +59,7 @@ def recipe_fg(recipe):
         ) / 200
     )
     return '{:.3f}'.format(
-        round(1 + (og - 1 - og_delta)*(1 - attenuation) + og_delta, 3)
+        round(1 + (og - 1 - og_delta) * (1 - attenuation) + og_delta, 3)
     )
 
 
@@ -123,9 +123,11 @@ def sort_hops(hops, form=False):
             by_use[hop['use']].append(hop)
 
     if form:
-        key = lambda hop: float(hop.duration.data)
+        def key(hop):
+            return float(hop.duration.data)
     else:
-        key = lambda hop: float(hop['duration'])
+        def key(hop):
+            return float(hop['duration'])
 
     hops_sorted = sorted(by_use['FWH'], key=key, reverse=True)
     hops_sorted.extend(sorted(by_use['Boil'], key=key, reverse=True))
@@ -145,7 +147,7 @@ def ferm_pct(fermentables):
         total += float(ferm['amount'])
     # Add a pct to each ferm
     for ferm in fermentables:
-        ferm['pct'] = 100*float(ferm['amount'])/total
+        ferm['pct'] = 100 * float(ferm['amount']) / total
     return fermentables
 
 
diff --git a/src/humulus/recipes.py b/src/humulus/recipes.py
index fde93f2..525f16c 100644
--- a/src/humulus/recipes.py
+++ b/src/humulus/recipes.py
@@ -37,8 +37,8 @@ bp = Blueprint('recipes', __name__, url_prefix='/recipes')
 class FermentableForm(Form):
     """Form for fermentables.
 
-    CSRF is disabled for this form.yeast.form (using `Form as parent class) because it
-    is never used by itself.
+    CSRF is disabled for this form.yeast.form (using `Form as parent class)
+    because it is never used by itself.
     """
     name = StringField('Name', validators=[DataRequired()])
     type = SelectField('Type', validators=[DataRequired()],
@@ -67,8 +67,8 @@ class FermentableForm(Form):
 class HopForm(Form):
     """Form for hops.
 
-    CSRF is disabled for this form.yeast.form (using `Form as parent class) because it
-    is never used by itself.
+    CSRF is disabled for this form.yeast.form (using `Form as parent class)
+    because it is never used by itself.
     """
     name = StringField('Name', validators=[DataRequired()])
     use = SelectField('Usage', validators=[DataRequired()],
@@ -96,8 +96,8 @@ class HopForm(Form):
 class YeastForm(Form):
     """Form for yeast.
 
-    CSRF is disabled for this form.yeast.form (using `Form as parent class) because it
-    is never used by itself.
+    CSRF is disabled for this form.yeast.form (using `Form as parent class)
+    because it is never used by itself.
     """
     name = StringField('Name', validators=[Optional()])
     type = SelectField('Type', default='',
@@ -192,10 +192,10 @@ class RecipeForm(FlaskForm):
         recipe['fermentables'] = [f.doc for f in self.fermentables]
         recipe['hops'] = [h.doc for h in self.hops]
         if (
-                self.yeast.doc['name'] and
-                self.yeast.doc['low_attenuation'] != "None" and
-                self.yeast.doc['high_attenuation'] != "None"
-            ):
+            self.yeast.doc['name'] and
+            self.yeast.doc['low_attenuation'] != "None" and
+            self.yeast.doc['high_attenuation'] != "None"
+        ):
             recipe['yeast'] = self.yeast.doc
         return recipe
 
@@ -360,7 +360,7 @@ def update(id):
                     'Your changes have been lost.'.format(recipe['name'])
                 ),
                 'danger'
-                )
+            )
             return redirect(url_for('recipes.info', id=id))
         # Copy values from submitted form to the existing recipe and save
         for key, value in form.doc.items():
diff --git a/src/humulus/styles.py b/src/humulus/styles.py
index 1b32a68..388fbb3 100644
--- a/src/humulus/styles.py
+++ b/src/humulus/styles.py
@@ -65,23 +65,26 @@ def sub_to_doc(sub):
     doc['ibu']['low'] = (sub.find('./stats/ibu/low').text
                          if sub.find('./stats/ibu/low') is not None else '0')
     doc['ibu']['high'] = (sub.find('./stats/ibu/high').text
-                         if sub.find('./stats/ibu/high') is not None else '100')
+                          if sub.find('./stats/ibu/high') is not None
+                          else '100')
     doc['og']['low'] = (sub.find('./stats/og/low').text
-                         if sub.find('./stats/og/low') is not None else '1.0')
+                        if sub.find('./stats/og/low') is not None else '1.0')
     doc['og']['high'] = (sub.find('./stats/og/high').text
                          if sub.find('./stats/og/high') is not None else '1.2')
     doc['fg']['low'] = (sub.find('./stats/fg/low').text
-                         if sub.find('./stats/fg/low') is not None else '1.0')
+                        if sub.find('./stats/fg/low') is not None else '1.0')
     doc['fg']['high'] = (sub.find('./stats/fg/high').text
                          if sub.find('./stats/fg/high') is not None else '1.2')
     doc['srm']['low'] = (sub.find('./stats/srm/low').text
                          if sub.find('./stats/srm/low') is not None else '0')
     doc['srm']['high'] = (sub.find('./stats/srm/high').text
-                         if sub.find('./stats/srm/high') is not None else '100')
+                          if sub.find('./stats/srm/high') is not None
+                          else '100')
     doc['abv']['low'] = (sub.find('./stats/abv/low').text
                          if sub.find('./stats/abv/low') is not None else '0')
     doc['abv']['high'] = (sub.find('./stats/abv/high').text
-                         if sub.find('./stats/abv/high') is not None else '100')
+                          if sub.find('./stats/abv/high') is not None
+                          else '100')
     return doc
 
 
@@ -121,10 +124,10 @@ def get_styles_list():
 def import_command():
     """CLI command to import BJCP styles."""
     url = current_app.config.get(
-            'BJCP_STYLES_URL',
-            ('https://raw.githubusercontent.com/meanphil'
-             '/bjcp-guidelines-2015/master/styleguide.xml')
-        )
+        'BJCP_STYLES_URL',
+        ('https://raw.githubusercontent.com/meanphil'
+         '/bjcp-guidelines-2015/master/styleguide.xml')
+    )
     import_styles(url)
     click.echo("Imported BJCP styles.")
 
@@ -153,11 +156,11 @@ def index():
 
     return render_template(
         'styles/index.html',
-        rows=rows[(page-1)*limit:page*limit],
+        rows=rows[(page - 1) * limit:page * limit],
         descending=descending,
         sort_by=sort_by,
         page=page,
-        num_pages=math.ceil(len(rows)/limit),
+        num_pages=math.ceil(len(rows) / limit),
         limit=limit
     )
 
diff --git a/tests/conftest.py b/tests/conftest.py
index 52bd0c3..21043e4 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -20,6 +20,7 @@ import pytest
 from humulus import create_app
 from humulus.couch import build_couch, get_couch, put_doc
 
+
 @pytest.fixture
 def app():
     dbname = 'test_{}'.format(str(uuid.uuid4()))
@@ -126,7 +127,8 @@ def app():
         })
 
         # Add a test style
-        put_doc({'$type': 'style',
+        put_doc({
+            '$type': 'style',
             '_id': '1A',
             'abv': {'high': '100', 'low': '0'},
             'appearance': 'Good looking',
diff --git a/tests/test_auth.py b/tests/test_auth.py
index 147b021..ed30b2c 100644
--- a/tests/test_auth.py
+++ b/tests/test_auth.py
@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from flask import session
-
 
 def test_login(client, auth):
     # Test GET
@@ -43,6 +41,7 @@ def test_login(client, auth):
         assert session['logged_in']
         assert session.permanent
 
+
 def test_logout(client, auth):
     # Login
     auth.login()
diff --git a/tests/test_couch.py b/tests/test_couch.py
index d276125..33c8805 100644
--- a/tests/test_couch.py
+++ b/tests/test_couch.py
@@ -12,10 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import uuid
 from pathlib import Path
 
-from humulus.couch import *
+from humulus.couch import put_doc, get_doc, update_doc, put_designs, get_view
 
 
 def test_put_doc(app):
@@ -73,7 +72,7 @@ def test_put_designs(app, monkeypatch):
 
     with app.app_context():
         # Test initial load of designs
-        monkeypatch.setattr(Path, 'parent', testpath/'assets/initial')
+        monkeypatch.setattr(Path, 'parent', testpath / 'assets/initial')
         put_designs()
 
         recipes = get_doc('_design/recipes')
@@ -86,7 +85,7 @@ def test_put_designs(app, monkeypatch):
         assert recipes['_rev'] == rev
 
         # Test that changes can be loaded
-        monkeypatch.setattr(Path, 'parent', testpath/'assets/changed')
+        monkeypatch.setattr(Path, 'parent', testpath / 'assets/changed')
         put_designs()
         recipes = get_doc('_design/recipes')
         assert 'by-date' in recipes['views']
diff --git a/tests/test_filters.py b/tests/test_filters.py
index b6928df..de6bbf7 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -14,7 +14,8 @@
 
 from decimal import Decimal
 
-from humulus.filters import *
+from humulus.filters import (recipe_abv, recipe_fg, recipe_ibu, sort_hops,
+                             recipe_ibu_ratio, recipe_og, recipe_srm, ferm_pct)
 from humulus.recipes import HopForm
 
 
diff --git a/tests/test_recipes.py b/tests/test_recipes.py
index 6b1a1fd..b1c69f1 100644
--- a/tests/test_recipes.py
+++ b/tests/test_recipes.py
@@ -16,7 +16,7 @@ import json
 from decimal import Decimal
 from io import BytesIO
 
-from humulus.couch import get_db, get_doc, put_doc
+from humulus.couch import get_doc
 from humulus.recipes import FermentableForm, HopForm, RecipeForm, YeastForm
 
 
@@ -41,7 +41,6 @@ def test_index(client):
         response.data
     )
 
-
     # Test sort by name descending
     response = client.get('/recipes/?descending=true&sort_by=name')
     assert (
@@ -119,6 +118,7 @@ def test_index(client):
         response.data
     )
 
+
 def test_create(client, app, auth):
     """Test success in creating a recipe document."""
     # Test GET without login
@@ -203,7 +203,7 @@ def test_update(client, app, auth):
                            query_string={'rev': ''}, data=doc)
     assert response.status_code == 302
     with client.session_transaction() as session:
-         flash_message = dict(session['_flashes']).pop('danger', None)
+        flash_message = dict(session['_flashes']).pop('danger', None)
     assert 'Update conflict' in flash_message
 
 
diff --git a/tests/test_styles.py b/tests/test_styles.py
index 4afc118..ca8d5ae 100644
--- a/tests/test_styles.py
+++ b/tests/test_styles.py
@@ -145,20 +145,21 @@ def test_import_styles(monkeypatch):
     monkeypatch.setattr('humulus.styles.put_doc', fake_put_doc)
 
     import_styles(None)
-    assert PutRecorder.doc == {'$type': 'style',
-            '_id': '1A',
-            'abv': {'high': '100', 'low': '0'},
-            'appearance': 'Good looking',
-            'aroma': 'Smelly',
-            'fg': {'high': '1.2', 'low': '1.0'},
-            'flavor': 'Good tasting',
-            'ibu': {'high': '100', 'low': '0'},
-            'impression': 'Refreshing',
-            'mouthfeel': 'Good feeling',
-            'name': 'Test Style',
-            'og': {'high': '1.2', 'low': '1.0'},
-            'srm': {'high': '100', 'low': '0'}
-        }
+    assert PutRecorder.doc == {
+        '$type': 'style',
+        '_id': '1A',
+        'abv': {'high': '100', 'low': '0'},
+        'appearance': 'Good looking',
+        'aroma': 'Smelly',
+        'fg': {'high': '1.2', 'low': '1.0'},
+        'flavor': 'Good tasting',
+        'ibu': {'high': '100', 'low': '0'},
+        'impression': 'Refreshing',
+        'mouthfeel': 'Good feeling',
+        'name': 'Test Style',
+        'og': {'high': '1.2', 'low': '1.0'},
+        'srm': {'high': '100', 'low': '0'}
+    }
 
     MockDB.db = {'1A': ''}
     PutRecorder.doc = None