diff --git a/tests/std/tests/VSO_0000000_vector_algorithms/test.cpp b/tests/std/tests/VSO_0000000_vector_algorithms/test.cpp
index 8498602479..9625a14cb4 100644
--- a/tests/std/tests/VSO_0000000_vector_algorithms/test.cpp
+++ b/tests/std/tests/VSO_0000000_vector_algorithms/test.cpp
@@ -1218,12 +1218,31 @@ void test_bitset(mt19937_64& gen) {
     test_randomized_bitset_base_count<512 - 5, 32 + 10>(gen);
 }
 
+template <class T>
+void test_case_string_find(const basic_string<T>& input_haystack, const T ch) {
+    const auto expected_iter = last_known_good_find(input_haystack.begin(), input_haystack.end(), ch);
+    const auto expected =
+        (expected_iter != input_haystack.end()) ? expected_iter - input_haystack.begin() : ptrdiff_t{-1};
+    const auto actual = static_cast<ptrdiff_t>(input_haystack.find(ch));
+    assert(expected == actual);
+}
+
+template <class T>
+void test_case_string_rfind(const basic_string<T>& input_haystack, const T ch) {
+    const auto expected_iter = last_known_good_find_last(input_haystack.begin(), input_haystack.end(), ch);
+    const auto expected =
+        (expected_iter != input_haystack.end()) ? expected_iter - input_haystack.begin() : ptrdiff_t{-1};
+    const auto actual = static_cast<ptrdiff_t>(input_haystack.rfind(ch));
+    assert(expected == actual);
+}
+
 template <class T>
 void test_case_string_find_first_of(const basic_string<T>& input_haystack, const basic_string<T>& input_needle) {
-    auto expected_iter = last_known_good_find_first_of(
+    const auto expected_iter = last_known_good_find_first_of(
         input_haystack.begin(), input_haystack.end(), input_needle.begin(), input_needle.end());
-    auto expected = (expected_iter != input_haystack.end()) ? expected_iter - input_haystack.begin() : ptrdiff_t{-1};
-    auto actual   = static_cast<ptrdiff_t>(input_haystack.find_first_of(input_needle));
+    const auto expected =
+        (expected_iter != input_haystack.end()) ? expected_iter - input_haystack.begin() : ptrdiff_t{-1};
+    const auto actual = static_cast<ptrdiff_t>(input_haystack.find_first_of(input_needle));
     assert(expected == actual);
 }
 
@@ -1242,8 +1261,8 @@ size_t last_known_good_find_last_of(const basic_string<T>& h, const basic_string
 
 template <class T>
 void test_case_string_find_last_of(const basic_string<T>& input_haystack, const basic_string<T>& input_needle) {
-    size_t expected = last_known_good_find_last_of(input_haystack, input_needle);
-    size_t actual   = input_haystack.find_last_of(input_needle);
+    const size_t expected = last_known_good_find_last_of(input_haystack, input_needle);
+    const size_t actual   = input_haystack.find_last_of(input_needle);
     assert(expected == actual);
 }
 
@@ -1255,6 +1274,10 @@ void test_basic_string_dis(mt19937_64& gen, D& dis) {
     input_needle.reserve(needleDataCount);
 
     for (;;) {
+        const T ch = static_cast<T>(dis(gen));
+        test_case_string_find(input_haystack, ch);
+        test_case_string_rfind(input_haystack, ch);
+
         input_needle.clear();
 
         test_case_string_find_first_of(input_haystack, input_needle);