diff --git a/README.md b/README.md
index 5da2601..2ca2d33 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ Eris maintains an up-to-date set of reports for every file in a codebase.
     # git clone https://github.com/ahamilton/eris
     # cd eris
     # ./install-dependencies
-    # python3.8 -m pip install .
+    # python3.7 -m pip install .
 
 To test its working properly:
 
diff --git a/appimage/AppRun b/appimage/AppRun
index 8c1daa9..2fa6541 100755
--- a/appimage/AppRun
+++ b/appimage/AppRun
@@ -13,7 +13,7 @@ export PATH="${HERE}"/usr/bin/:"${HERE}"/usr/local/bin/:"${PATH}"
 export UNION_PRELOAD="${HERE}"
 export LD_PRELOAD="${HERE}/libunionpreload.so"
 export LD_LIBRARY_PATH="${HERE}"/usr/lib/:"${HERE}"/usr/lib/i386-linux-gnu/:"${HERE}"/usr/lib/x86_64-linux-gnu/:"${HERE}"/usr/lib32/:"${HERE}"/usr/lib64/:"${HERE}"/lib/:"${HERE}"/lib/i386-linux-gnu/:"${HERE}"/lib/x86_64-linux-gnu/:"${HERE}"/lib32/:"${HERE}"/lib64/:"${LD_LIBRARY_PATH}"
-export PYTHONPATH=/usr/local/lib/python3.8/dist-packages:"${PYTHONPATH}"
+export PYTHONPATH=/usr/local/lib/python3.7/dist-packages:"${PYTHONPATH}"
 if [ -z $APPIMAGE_ENTER ]; then
     EXEC=$(grep -e '^Exec=.*' "${HERE}"/*.desktop | head -n 1 | cut -d "=" -f 2- | sed -e 's|%.||g')
     exec ${EXEC} $@
diff --git a/build-flatpak.py b/build-flatpak.py
index 61a0399..f60de7d 100755
--- a/build-flatpak.py
+++ b/build-flatpak.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python3.8
+#!/usr/bin/python3.7
 
 # Copyright (C) 2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/eris/__main__.py b/eris/__main__.py
index d8973c9..e446868 100755
--- a/eris/__main__.py
+++ b/eris/__main__.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
diff --git a/eris/gut.py b/eris/gut.py
index cd69bb3..fd8b49b 100755
--- a/eris/gut.py
+++ b/eris/gut.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/eris/pydoc_color.py b/eris/pydoc_color.py
index b35cd81..4404175 100755
--- a/eris/pydoc_color.py
+++ b/eris/pydoc_color.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/eris/tools.py b/eris/tools.py
index bde4d11..7150fa2 100755
--- a/eris/tools.py
+++ b/eris/tools.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python3.8
+#!/usr/bin/python3.7
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
@@ -34,7 +34,7 @@ import eris.lscolors as lscolors
 import eris.termstr as termstr
 
 
-PYTHON_VERSION = "3.8"
+PYTHON_VERSION = "3.7"
 PYTHON_EXECUTABLE = "python" + PYTHON_VERSION
 CACHE_PATH = ".eris"
 
@@ -303,11 +303,11 @@ def pytest(path):
 
 @deps(deps={"pip/mypy"}, url="http://mypy-lang.org/", executables={"mypy"})
 def mypy(path):
-    env = os.environ.copy()
-    env["MYPY_FORCE_COLOR"] = "1"
-    return _run_command([PYTHON_EXECUTABLE, "-m", "mypy", "--color-output",
-                         "--ignore-missing-imports", "--pretty", path],
-                        timeout=TIMEOUT, has_color=True, env=env)
+    stdout, stderr, returncode = _do_command(
+        [PYTHON_EXECUTABLE, "-m", "mypy", "--ignore-missing-imports", path],
+        timeout=TIMEOUT)
+    status = Status.ok if returncode == 0 else Status.problem
+    return status, stdout
 
 
 def _colorize_coverage_report(lines):
diff --git a/eris/tools.toml b/eris/tools.toml
index 26ea578..b277eba 100644
--- a/eris/tools.toml
+++ b/eris/tools.toml
@@ -49,7 +49,7 @@ tools_for_extensions = [
 [python_syntax]
   dependencies = []
   url = "https://en.wikipedia.org/wiki/Python_syntax_and_semantics"
-  command = "python3.8 -m py_compile"
+  command = "python3.7 -m py_compile"
 
 [pydoc]
   dependencies = []
@@ -63,34 +63,34 @@ tools_for_extensions = [
 [pycodestyle]
   dependencies = ["pip/pycodestyle"]
   url = "http://pycodestyle.pycqa.org/en/latest/"
-  command = "python3.8 -m pycodestyle"
+  command = "python3.7 -m pycodestyle"
 
 [pydocstyle]
   dependencies = ["pip/pydocstyle"]
   url = "http://www.pydocstyle.org/en/2.1.1/usage.html"
-  command = "python3.8 -m pydocstyle --ignore=D1,D213"
+  command = "python3.7 -m pydocstyle --ignore=D1,D213"
 
 [pyflakes]
   dependencies = ["pip/pyflakes"]
   url = "https://pypi.org/project/pyflakes/"
-  command = "python3.8 -m pyflakes"
+  command = "python3.7 -m pyflakes"
 
 [pylint]
   dependencies = ["pip/pylint"]
   url = "https://www.pylint.org/"
-  command = "python3.8 -m pylint -f colorized --errors-only"
+  command = "python3.7 -m pylint -f colorized --errors-only"
   has_color = true
 
 [python_modulefinder]
   dependencies = []
   url = "https://docs.python.org/3/library/modulefinder.html"
-  command = "python3.8 -m modulefinder"
+  command = "python3.7 -m modulefinder"
   success_status = "normal"
 
 [bandit]
   dependencies = ["pip/bandit"]
   url = "https://pypi.org/project/bandit/"
-  command = "python3.8 -m bandit.cli.main -f screen"
+  command = "python3.7 -m bandit.cli.main -f screen"
   has_color = true
   timeout = 60
 
@@ -132,7 +132,7 @@ tools_for_extensions = [
 [dis]
   dependencies = []
   url = "https://docs.python.org/3/library/dis.html"
-  command = "python3.8 -m dis"
+  command = "python3.7 -m dis"
   success_status = "normal"
 
 [objdump_headers]
@@ -303,7 +303,7 @@ tools_for_extensions = [
 [yamllint]
   dependencies = ["pip/yamllint"]
   url = "https://github.com/adrienverge/yamllint"
-  command = "python3.8 -m yamllint -f colored"
+  command = "python3.7 -m yamllint -f colored"
   has_color = true
 
 [mediainfo]
diff --git a/eris/webserver.py b/eris/webserver.py
index befc98b..6a83fd1 100755
--- a/eris/webserver.py
+++ b/eris/webserver.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2018-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/eris/worker.py b/eris/worker.py
index c46c0c7..61a6ad8 100755
--- a/eris/worker.py
+++ b/eris/worker.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/install-dependencies b/install-dependencies
index 6c3e916..76439fd 100755
--- a/install-dependencies
+++ b/install-dependencies
@@ -13,8 +13,8 @@ if [ $DIST_ID != "ubuntu" ]; then
     exit 1
 fi
 echo "Installing the dependencies of the eris script…"
-sudo apt --yes install python3-pip python3.8 util-linux
-python3.8 -m pip install pyinotify pygments docopt pillow toml
+sudo apt --yes install python3-pip python3.7 util-linux
+python3.7 -m pip install pyinotify pygments docopt pillow toml
 echo
 echo "Installing all the tools eris may need…"
 ./install-tools
diff --git a/install-tools b/install-tools
index 3529289..7741a33 100755
--- a/install-tools
+++ b/install-tools
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/make-appimage.py b/make-appimage.py
index 41dd95c..6f499d3 100755
--- a/make-appimage.py
+++ b/make-appimage.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2017-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/make-flatpak-manifest.py b/make-flatpak-manifest.py
index 2ce414a..f1c3681 100755
--- a/make-flatpak-manifest.py
+++ b/make-flatpak-manifest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python3.8
+#!/usr/bin/python3.7
 
 # Copyright (C) 2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
@@ -106,7 +106,7 @@ def haskell_modules(dep):
 
 
 def python_modules(package):
-    python_version = "python3.8"
+    python_version = "python3.7"
     with tempfile.TemporaryDirectory() as temp_dir:
         output = subprocess.check_output(
             [python_version, "-m", "pip", "download", "--dest", temp_dir,
@@ -398,7 +398,7 @@ def eris_modules():
     modules.append({"name": "eris",
                     "buildsystem": "simple",
                     "build-commands": [
-                        "python3.8 -m pip install --no-index --prefix=/app .",
+                        "python3.7 -m pip install --no-index --prefix=/app .",
                         "cp -a tests test-all /app/bin"],
                     "sources": [{"type": "git", "url": eris_url,
                                  "commit": get_latest_commit()}]})
diff --git a/make-readme.py b/make-readme.py
index bb17f02..423dec3 100755
--- a/make-readme.py
+++ b/make-readme.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
@@ -36,7 +36,7 @@ Eris maintains an up-to-date set of reports for every file in a codebase.
     # git clone https://github.com/ahamilton/eris
     # cd eris
     # ./install-dependencies
-    # python3.8 -m pip install .
+    # python3.7 -m pip install .
 
 To test its working properly:
 
diff --git a/setup.py b/setup.py
index b155930..cd57867 100755
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2017-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/test_distributions.py b/test_distributions.py
index 7230036..c4f1be4 100755
--- a/test_distributions.py
+++ b/test_distributions.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2017-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/__main___test.py b/tests/__main___test.py
index d532617..89e7555 100755
--- a/tests/__main___test.py
+++ b/tests/__main___test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/fill3_test.py b/tests/fill3_test.py
index 44187b7..d987e70 100755
--- a/tests/fill3_test.py
+++ b/tests/fill3_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
diff --git a/tests/golden-files/results/mypy-hi3_py b/tests/golden-files/results/mypy-hi3_py
index 953416d..e69de29 100644
--- a/tests/golden-files/results/mypy-hi3_py
+++ b/tests/golden-files/results/mypy-hi3_py
@@ -1,2 +0,0 @@
-Success: no issues found in 1 source file
-
\ No newline at end of file
diff --git a/tests/gut_test.py b/tests/gut_test.py
index ca3e36e..f2674fd 100755
--- a/tests/gut_test.py
+++ b/tests/gut_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/lscolors_test.py b/tests/lscolors_test.py
index c71950a..823e28e 100755
--- a/tests/lscolors_test.py
+++ b/tests/lscolors_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2011, 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/paged_list_test.py b/tests/paged_list_test.py
index ca2c45a..26f0f6e 100755
--- a/tests/paged_list_test.py
+++ b/tests/paged_list_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/termstr_test.py b/tests/termstr_test.py
index 114b22a..522f7e6 100755
--- a/tests/termstr_test.py
+++ b/tests/termstr_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2015-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/tools_test.py b/tests/tools_test.py
index 216753a..804671e 100755
--- a/tests/tools_test.py
+++ b/tests/tools_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2016-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.
diff --git a/tests/worker_test.py b/tests/worker_test.py
index 29d0a40..0f07a97 100755
--- a/tests/worker_test.py
+++ b/tests/worker_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.8
+#!/usr/bin/env python3.7
 
 # Copyright (C) 2016-2019 Andrew Hamilton. All rights reserved.
 # Licensed under the Artistic License 2.0.