diff --git a/sorting/binary_insertion_sort.cpp b/sorting/binary_insertion_sort.cpp
index 32514e2f1..6a64d6dd0 100644
--- a/sorting/binary_insertion_sort.cpp
+++ b/sorting/binary_insertion_sort.cpp
@@ -99,7 +99,7 @@ void insertionSort_binsrch(std::vector<T> &arr) {
  * @brief Self-test implementations
  * @returns void
  */
-void test() {
+static void test() {
     /* descriptions of the following test */
     /* 1st test: 
        [5, -3, -1, -2, 7] returns [-3, -2, -1, 5, 7] */