diff --git a/dist/tools/licenses/check.sh b/dist/tools/licenses/check.sh
index f860b82eaf..74edd966b8 100755
--- a/dist/tools/licenses/check.sh
+++ b/dist/tools/licenses/check.sh
@@ -1,11 +1,14 @@
 #!/bin/sh
 
+# Copyright 2017 Kaspar Schleiser <kaspar@schleiser.de>
 # Copyright 2014 Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
 #
 # This file is subject to the terms and conditions of the GNU Lesser
 # General Public License v2.1. See the file LICENSE in the top level
 # directory for more details.
 
+. ${RIOTBASE:+${RIOTBASE}/}dist/tools/ci/changed_files.sh
+
 # customizable
 CHECKROOT=$(dirname "${0}")
 LICENSEDIR="${CHECKROOT}/patterns"
@@ -20,7 +23,8 @@ TAB_CHAR="$(printf '\t')"
 ROOT=$(git rev-parse --show-toplevel)
 LICENSES=$(ls "${LICENSEDIR}")
 EXIT_CODE=0
-ERROR_EXIT_CODE="1"
+
+: ${ERROR_EXIT_CODE:=1}
 
 # reset output dir
 rm -fr "${OUTPUT}"
@@ -29,39 +33,7 @@ for LICENSE in ${LICENSES}; do
     echo -n '' > "${OUTPUT}/${LICENSE}"
 done
 
-# If no branch but an option is given, unset BRANCH.
-# Otherwise, consume this parameter.
-BRANCH="${1}"
-if echo "${BRANCH}" | grep -q '^-'; then
-    BRANCH=""
-else
-    if [ -n "${BRANCH}" ]; then
-        shift 1
-    fi
-fi
-
-# If the --diff-filter option is given, consume this parameter.
-# Set the default DIFFFILTER option otherwise.
-DIFFFILTER="${1}"
-if echo "${DIFFFILTER}" | grep -q '^--diff-filter='; then
-    shift 1
-else
-    DIFFFILTER="--diff-filter=ACMR"
-fi
-
-# If the --error-exitcode option is given, consume this parameter
-# and overwrite the default ERROR_EXIT_CODE.
-if echo "${1}" | grep -q '^--error-exitcode='; then
-    ERROR_EXIT_CODE=$(echo ${1} | sed -e 's/--error-exitcode=//')
-    shift 1
-fi
-
-# select files to check
-if [ -z "${BRANCH}" ]; then
-    FILES="$(git ls-tree -r --full-tree --name-only HEAD | grep -E '\.([sSch]|cpp)$')"
-else
-    FILES="$(git diff ${DIFFFILTER} --name-only ${BRANCH} | grep -E '\.([sSchp]|cpp)$')"
-fi
+FILES=$(FILEREGEX='\.([sSch]|cpp)$' changed_files)
 
 # categorize files
 for FILE in ${FILES}; do