diff --git a/tools/fast8.sh b/tools/fast8.sh
index 2b3e22abda5..22976ce09b8 100755
--- a/tools/fast8.sh
+++ b/tools/fast8.sh
@@ -1,7 +1,17 @@
 #!/bin/bash
 
+NUM_COMMITS=${FAST8_NUM_COMMITS:-1}
+
+if [[ $NUM_COMMITS = "smart" ]]; then
+    # Run on all commits not submitted yet
+    # (sort of -- only checks vs. "master" since this is easy)
+    NUM_COMMITS=$(git cherry master | wc -l)
+fi
+
+echo "Checking last $NUM_COMMITS commits."
+
 cd $(dirname "$0")/..
-CHANGED=$(git diff --name-only HEAD~1 | tr '\n' ' ')
+CHANGED=$(git diff --name-only HEAD~${NUM_COMMITS} | tr '\n' ' ')
 
 # Skip files that don't exist
 # (have been git rm'd)
diff --git a/tox.ini b/tox.ini
index cc5b8434237..7cad0e821d8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -91,6 +91,7 @@ basepython = python3
 envdir = {toxworkdir}/pep8
 commands =
   {toxinidir}/tools/fast8.sh
+passenv = FAST8_NUM_COMMITS
 
 [testenv:pylint]
 basepython = python3