diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index cc13e4a9..b68332c8 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,5 +1,5 @@
 repos:
-    -   
+    -
         repo: https://github.com/pre-commit/mirrors-isort
         rev: v4.3.21
         hooks:
@@ -7,14 +7,14 @@ repos:
               language_version: python3.7
     -
         repo: 'https://github.com/psf/black'
-        rev: stable
+        rev: 19.10b0
         hooks:
             - id: black
               args: ['--safe']
               language_version: python3.7
     -
         repo: 'https://github.com/pre-commit/pre-commit-hooks'
-        rev: v2.4.0 
+        rev: v2.4.0
         hooks:
             - id: flake8
               language_version: python3.7
@@ -36,9 +36,9 @@ repos:
                  # Don't require docstrings for tests
                  '--match=(?!test).*\.py']
 
-    -   
+    -
         repo: https://github.com/pre-commit/mirrors-mypy
         rev: 'v0.770'
         hooks:
             -   id: mypy
-                args: [--no-strict-optional, --ignore-missing-imports]
\ No newline at end of file
+                args: [--no-strict-optional, --ignore-missing-imports]