diff --git a/tests/src/unit-bson.cpp b/tests/src/unit-bson.cpp
index b4756c9b5..09321e3d5 100644
--- a/tests/src/unit-bson.cpp
+++ b/tests/src/unit-bson.cpp
@@ -1311,7 +1311,7 @@ TEST_CASE("BSON declared document size bounds the content")
     // records the events that a SAX parser receives
     struct recorder : nlohmann::json_sax<json>
     {
-        std::string events;
+        std::string events {};
 
         bool null() override
         {
diff --git a/tests/src/unit-json_patch.cpp b/tests/src/unit-json_patch.cpp
index b6c78532d..cc1b26a40 100644
--- a/tests/src/unit-json_patch.cpp
+++ b/tests/src/unit-json_patch.cpp
@@ -2178,8 +2178,13 @@ TEST_CASE("JSON patch - behavior documented in the API reference")
 
     SECTION("patch() has the strong guarantee")
     {
-        const json doc = R"({"a": [1, 2], "o": {"k": "v"}})"_json;
-        const json before = doc;
+        // independent values, so that the comparison below checks the untouched document
+        const auto make_doc = []
+        {
+            return R"({"a": [1, 2], "o": {"k": "v"}})"_json;
+        };
+        const json doc = make_doc();
+        const json before = make_doc();
 
         const std::vector<json> failing =
         {
@@ -2202,7 +2207,7 @@ TEST_CASE("JSON patch - behavior documented in the API reference")
             CHECK_THROWS_AS(doc.patch(patch), json::exception&);
             CHECK(doc == before);
 
-            json copy = doc;
+            json copy = make_doc();
             CHECK_THROWS_AS(copy.patch(patch), json::exception&);
             CHECK(copy == before);
         }
diff --git a/tests/src/unit-json_view_builder.cpp b/tests/src/unit-json_view_builder.cpp
index 1074f7018..4023c7848 100644
--- a/tests/src/unit-json_view_builder.cpp
+++ b/tests/src/unit-json_view_builder.cpp
@@ -592,7 +592,7 @@ TEST_CASE("json_view node integer bits")
                 })
         {
             CAPTURE(v)
-            n.kind = static_cast<nlohmann::detail::view::node_kind>(0x5A);
+            n.kind = nlohmann::detail::view::node_kind::link;
             n.flags = 0xA5;
             n.extra = 0x1234;
             n.off = 0x89ABCDEFu;
@@ -601,7 +601,7 @@ TEST_CASE("json_view node integer bits")
             CHECK(n.len == static_cast<std::uint32_t>(v));
             CHECK(n.next == static_cast<std::uint32_t>(v >> 32));
             // the other fields are untouched
-            CHECK(static_cast<std::uint8_t>(n.kind) == 0x5A);
+            CHECK(n.kind == nlohmann::detail::view::node_kind::link);
             CHECK(n.flags == 0xA5);
             CHECK(n.extra == 0x1234);
             CHECK(n.off == 0x89ABCDEFu);