diff --git a/formats/json-tests/jsTest/src/kotlinx/serialization/json/DecodeFromDynamicTest.kt b/formats/json-tests/jsTest/src/kotlinx/serialization/json/DecodeFromDynamicTest.kt
index 1a0c29c2c4..5015360bee 100644
--- a/formats/json-tests/jsTest/src/kotlinx/serialization/json/DecodeFromDynamicTest.kt
+++ b/formats/json-tests/jsTest/src/kotlinx/serialization/json/DecodeFromDynamicTest.kt
@@ -4,6 +4,7 @@
 
 package kotlinx.serialization.json
 
+import kotlinx.serialization.builtins.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
 import kotlinx.serialization.*
@@ -89,6 +90,11 @@ class DecodeFromDynamicTest {
         assertEquals(WithChar('a'), parsed3)
     }
 
+    @Test
+    fun dynamicNull() {
+        assertNull(Json.decodeFromDynamic(Data.serializer().nullable, null))
+    }
+
     @Test
     fun dynamicAllTypesTest() {
         val dyn = js("""{ b: 1, s: 2, i: 3, f: 1.0, d: 42.0, c: 'a', B: true, S: "str"}""")
diff --git a/formats/json-tests/jsTest/src/kotlinx/serialization/json/EncodeToDynamicTest.kt b/formats/json-tests/jsTest/src/kotlinx/serialization/json/EncodeToDynamicTest.kt
index 74196b7b7e..531742353c 100644
--- a/formats/json-tests/jsTest/src/kotlinx/serialization/json/EncodeToDynamicTest.kt
+++ b/formats/json-tests/jsTest/src/kotlinx/serialization/json/EncodeToDynamicTest.kt
@@ -126,6 +126,11 @@ class EncodeToDynamicTest {
         assertDynamicForm(WithLong(MAX_SAFE_INTEGER.unaryMinus().toLong()))
     }
 
+    @Test
+    fun dynamicNull() {
+        assertNull(Json.encodeToDynamic(Data.serializer().nullable, null))
+    }
+
     @Test
     fun wrappedObjectsTest() {
         assertDynamicForm(DataWrapper("a string", Data(42))) { data, serialized ->