diff --git a/contrib/scripts/checkpatch-feature-branch.sh b/contrib/scripts/checkpatch-feature-branch.sh
index 2e0b589194..e2fe5b422f 100755
--- a/contrib/scripts/checkpatch-feature-branch.sh
+++ b/contrib/scripts/checkpatch-feature-branch.sh
@@ -1,26 +1,35 @@
 #!/bin/bash
 
 die() {
-	printf "%s\n" "$@"
-	exit 1
+    printf "%s\n" "$@"
+    exit 1
 }
 
 HEAD="${1:-HEAD}"
 
 BASE_DIR="$(dirname "$0")"
 
-BASE_REF="refs/remotes/origin/"
+if printf '%s' "$HEAD" | grep -q '\.\.'; then
+    # Check the explicitly specified range from the argument.
+    REFS=( $(git log --reverse --format='%H' "$HEAD") ) || die "not a valid range (HEAD is $HEAD)"
+else
+    BASE_REF="refs/remotes/origin/"
 
-RANGES=( $(git show-ref | sed 's#^\(.*\) '"$BASE_REF"'\(master\|nm-1-[0-9]\+\)$#\1..'"$HEAD"'#p' -n) )
+    # the argument is only a single ref (or the default "HEAD").
+    # Find all commits that branch off one of the stable branches or master
+    # and lead to $HEAD. These are the commits of the feature branch.
 
-[ "${#RANGES[@]}" != 0 ] || die "cannot detect git-ranges (HEAD is $(git rev-parse HEAD))"
+    RANGES=( $(git show-ref | sed 's#^\(.*\) '"$BASE_REF"'\(master\|nm-1-[0-9]\+\)$#\1..'"$HEAD"'#p' -n) )
 
-REFS=( $(git log --reverse --format='%H' "${RANGES[@]}") )
+    [ "${#RANGES[@]}" != 0 ] || die "cannot detect git-ranges (HEAD is $(git rev-parse HEAD))"
 
-if [ "${#REFS[@]}" == 0 ] ; then
-	# no refs detected. This means, $HEAD is already on master (or one of the
-	# stable nm-1-* branches. Just check the patch itself.
-	REFS=( $HEAD )
+    REFS=( $(git log --reverse --format='%H' "${RANGES[@]}") )
+
+    if [ "${#REFS[@]}" == 0 ] ; then
+        # no refs detected. This means, $HEAD is already on master (or one of the
+        # stable nm-1-* branches. Just check the patch itself.
+        REFS=( $HEAD )
+    fi
 fi
 
 SUCCESS=0