diff --git a/examples/ProgmemExample/ProgmemExample.ino b/examples/ProgmemExample/ProgmemExample.ino
index 4de5347a..6c899faa 100644
--- a/examples/ProgmemExample/ProgmemExample.ino
+++ b/examples/ProgmemExample/ProgmemExample.ino
@@ -17,7 +17,7 @@ void setup() {
   DynamicJsonDocument doc(1024);
 
   // You can use a Flash String as your JSON input.
-  // WARNING: the string in the input  will be duplicated in the JsonDocument.
+  // WARNING: the strings in the input will be duplicated in the JsonDocument.
   deserializeJson(doc, F("{\"sensor\":\"gps\",\"time\":1351824120,"
                          "\"data\":[48.756080,2.302038]}"));
   JsonObject obj = doc.as<JsonObject>();
diff --git a/test/JsonVariant/is.cpp b/test/JsonVariant/is.cpp
index b9e17b77..c0e91d13 100644
--- a/test/JsonVariant/is.cpp
+++ b/test/JsonVariant/is.cpp
@@ -147,4 +147,16 @@ TEST_CASE("JsonVariant::is()") {
   SECTION("string") {
     testString("42");
   }
+
+  SECTION("null") {
+    DynamicJsonDocument doc(4096);
+    deserializeJson(doc, "[null]");
+    JsonVariant v = doc[0];
+
+    REQUIRE(v.is<bool>() == false);
+    REQUIRE(v.is<char *>() == false);
+    REQUIRE(v.is<int>() == false);
+    REQUIRE(v.is<std::string>() == false);
+    REQUIRE(v.is<float>() == false);
+  }
 }
diff --git a/test/JsonVariant/undefined.cpp b/test/JsonVariant/undefined.cpp
index 1e8fbf87..b27f3278 100644
--- a/test/JsonVariant/undefined.cpp
+++ b/test/JsonVariant/undefined.cpp
@@ -8,31 +8,63 @@
 TEST_CASE("JsonVariant undefined") {
   JsonVariant variant;
 
-  SECTION("as<long>()") {
-    REQUIRE(0 == variant.as<long>());
+  SECTION("as<T>()") {
+    SECTION("long") {
+      REQUIRE(variant.as<long>() == 0);
+    }
+
+    SECTION("unsigned") {
+      REQUIRE(variant.as<unsigned>() == 0);
+    }
+
+    SECTION("char*") {
+      REQUIRE(variant.as<char*>() == 0);
+    }
+
+    SECTION("double") {
+      REQUIRE(variant.as<double>() == 0);
+    }
+
+    SECTION("bool") {
+      REQUIRE(variant.as<bool>() == false);
+    }
+
+    SECTION("JsonArray") {
+      REQUIRE(variant.as<JsonArray>().isNull());
+    }
+
+    SECTION("JsonObject") {
+      REQUIRE(variant.as<JsonObject>().isNull());
+    }
   }
 
-  SECTION("as<unsigned>()") {
-    REQUIRE(0 == variant.as<unsigned>());
-  }
+  SECTION("is<T>()") {
+    SECTION("long") {
+      REQUIRE(variant.is<long>() == false);
+    }
 
-  SECTION("as<char*>()") {
-    REQUIRE(0 == variant.as<char*>());
-  }
+    SECTION("unsigned") {
+      REQUIRE(variant.is<unsigned>() == false);
+    }
 
-  SECTION("as<double>()") {
-    REQUIRE(0 == variant.as<double>());
-  }
+    SECTION("char*") {
+      REQUIRE(variant.is<char*>() == false);
+    }
 
-  SECTION("as<bool>()") {
-    REQUIRE(false == variant.as<bool>());
-  }
+    SECTION("double") {
+      REQUIRE(variant.is<double>() == false);
+    }
 
-  SECTION("as<JsonArray>()") {
-    REQUIRE(variant.as<JsonArray>().isNull());
-  }
+    SECTION("bool") {
+      REQUIRE(variant.is<bool>() == false);
+    }
 
-  SECTION("as<JsonObject>()") {
-    REQUIRE(variant.as<JsonObject>().isNull());
+    SECTION("JsonArray") {
+      REQUIRE(variant.is<JsonArray>() == false);
+    }
+
+    SECTION("JsonObject") {
+      REQUIRE(variant.is<JsonObject>() == false);
+    }
   }
 }