diff --git a/pre-commit.shellcheck b/pre-commit.shellcheck
index 3d87ed6..d24af67 100755
--- a/pre-commit.shellcheck
+++ b/pre-commit.shellcheck
@@ -30,7 +30,7 @@ function main {
 
 	declare -a files=()
 	while read -r file; do
-		files[${files[@]}+1]="$file"
+		files[${#files[@]}+1]="$file"
 	done < <(get_shell_files)
 
 	if [[ "${#files[@]}" -ne 0 ]]; then