diff --git a/tools/fast8.sh b/tools/fast8.sh
new file mode 100755
index 000000000..2b3e22abd
--- /dev/null
+++ b/tools/fast8.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+cd $(dirname "$0")/..
+CHANGED=$(git diff --name-only HEAD~1 | tr '\n' ' ')
+
+# Skip files that don't exist
+# (have been git rm'd)
+CHECK=""
+for FILE in $CHANGED; do
+    if [ -f "$FILE" ]; then
+        CHECK="$CHECK $FILE"
+    fi
+done
+
+diff -u --from-file /dev/null $CHECK | flake8 --diff
diff --git a/tox.ini b/tox.ini
index d907497f6..7a05dd770 100644
--- a/tox.ini
+++ b/tox.ini
@@ -22,7 +22,12 @@ whitelist_externals = bash
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
-commands = flake8
+commands = flake8 {posargs}
+
+[testenv:fast8]
+envdir = {toxworkdir}/pep8
+commands =
+    {toxinidir}/tools/fast8.sh
 
 [testenv:pylint]
 deps = -r{toxinidir}/requirements.txt