core/scripts/dev/commit-code-check.sh | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/core/scripts/dev/commit-code-check.sh b/core/scripts/dev/commit-code-check.sh
index ed08f77aeb..40a0cd733f 100755
--- a/core/scripts/dev/commit-code-check.sh
+++ b/core/scripts/dev/commit-code-check.sh
@@ -109,7 +109,12 @@
 
 TOP_LEVEL=$($GIT rev-parse --show-toplevel)
 
-DRUPAL_ROOT=${DRUPAL_ROOT:="$TOP_LEVEL"}
+# Determine the absolute path of this script.
+# Source: https://stackoverflow.com/a/1482133.
+SCRIPT_ABS_PATH=$(dirname -- "$( readlink -f -- "$0"; )")
+
+# The site root directory is 3 levels up from where the script is located.
+DRUPAL_ROOT=$(dirname $(dirname $(dirname $SCRIPT_ABS_PATH)))
 
 # This variable will be set to one when the file core/phpcs.xml.dist is changed.
 PHPCS_XML_DIST_FILE_CHANGED=0