diff --git a/tests/src/unit-ordered_json.cpp b/tests/src/unit-ordered_json.cpp
index 2c72b3e8c..8c07ffa16 100644
--- a/tests/src/unit-ordered_json.cpp
+++ b/tests/src/unit-ordered_json.cpp
@@ -534,9 +534,10 @@ TEST_CASE("object_key_index")
 
         // the hashes are not distinct on purpose: elements with the same
         // hash are told apart by the caller
-        const auto hash_of = [](std::size_t position)
+        const auto hash_of = [](std::size_t position) -> std::size_t
         {
-            return (position % 50) * 0x9E3779B97F4A7C15ull;
+            // truncated to 32 bits where std::size_t is that small
+            return static_cast<std::size_t>((position % 50) * 0x9E3779B97F4A7C15ull);
         };
 
         std::vector<std::size_t> hashes;
diff --git a/tests/src/unit-regression1.cpp b/tests/src/unit-regression1.cpp
index 9338365c8..53f501f07 100644
--- a/tests/src/unit-regression1.cpp
+++ b/tests/src/unit-regression1.cpp
@@ -1555,6 +1555,7 @@ TEST_CASE("regression tests 1")
         {
             my_json j = make();
 #ifdef JSON_NO_THREAD_LOCAL
+            // (set by the user, or by the library for clang with MinGW)
             // the objects below the outermost one are not copied by their
             // object_t here, but member by member, which keeps their
             // timestamps correct: "c" is not mistaken for "b" and is inserted