diff --git a/core/commonMain/src/kotlinx/serialization/internal/Primitives.kt b/core/commonMain/src/kotlinx/serialization/internal/Primitives.kt
index 71181ded4e..c26a0b831f 100644
--- a/core/commonMain/src/kotlinx/serialization/internal/Primitives.kt
+++ b/core/commonMain/src/kotlinx/serialization/internal/Primitives.kt
@@ -15,38 +15,9 @@ import kotlin.reflect.*
 import kotlin.time.Duration
 import kotlin.uuid.*
 
-@OptIn(ExperimentalUnsignedTypes::class, ExperimentalUuidApi::class)
-private val BUILTIN_SERIALIZERS = mapOf(
-    String::class to String.serializer(),
-    Char::class to Char.serializer(),
-    CharArray::class to CharArraySerializer(),
-    Double::class to Double.serializer(),
-    DoubleArray::class to DoubleArraySerializer(),
-    Float::class to Float.serializer(),
-    FloatArray::class to FloatArraySerializer(),
-    Long::class to Long.serializer(),
-    LongArray::class to LongArraySerializer(),
-    ULong::class to ULong.serializer(),
-    ULongArray::class to ULongArraySerializer(),
-    Int::class to Int.serializer(),
-    IntArray::class to IntArraySerializer(),
-    UInt::class to UInt.serializer(),
-    UIntArray::class to UIntArraySerializer(),
-    Short::class to Short.serializer(),
-    ShortArray::class to ShortArraySerializer(),
-    UShort::class to UShort.serializer(),
-    UShortArray::class to UShortArraySerializer(),
-    Byte::class to Byte.serializer(),
-    ByteArray::class to ByteArraySerializer(),
-    UByte::class to UByte.serializer(),
-    UByteArray::class to UByteArraySerializer(),
-    Boolean::class to Boolean.serializer(),
-    BooleanArray::class to BooleanArraySerializer(),
-    Unit::class to Unit.serializer(),
-    Nothing::class to NothingSerializer(),
-    Duration::class to Duration.serializer(),
-    Uuid::class to Uuid.serializer()
-)
+private val BUILTIN_SERIALIZERS = initBuiltins()
+
+internal expect fun initBuiltins(): Map<KClass<*>, KSerializer<*>>
 
 internal class PrimitiveSerialDescriptor(
     override val serialName: String,
diff --git a/core/jsMain/src/kotlinx/serialization/internal/Platform.kt b/core/jsMain/src/kotlinx/serialization/internal/Platform.kt
index 571c3f7979..e423afca2a 100644
--- a/core/jsMain/src/kotlinx/serialization/internal/Platform.kt
+++ b/core/jsMain/src/kotlinx/serialization/internal/Platform.kt
@@ -5,7 +5,10 @@
 package kotlinx.serialization.internal
 
 import kotlinx.serialization.*
+import kotlinx.serialization.builtins.*
 import kotlin.reflect.*
+import kotlin.time.*
+import kotlin.uuid.*
 
 internal actual fun <T> Array<T>.getChecked(index: Int): T {
     if (index !in indices) throw IndexOutOfBoundsException("Index $index out of bounds $indices")
@@ -77,3 +80,36 @@ private val KClass<*>.isInterface: Boolean
         if (this === Nothing::class) return false
         return js.asDynamic().`$metadata$`?.kind == "interface"
     }
+
+@OptIn(ExperimentalUnsignedTypes::class, ExperimentalUuidApi::class, ExperimentalSerializationApi::class)
+internal actual fun initBuiltins(): Map<KClass<*>, KSerializer<*>> = mapOf(
+    String::class to String.serializer(),
+    Char::class to Char.serializer(),
+    CharArray::class to CharArraySerializer(),
+    Double::class to Double.serializer(),
+    DoubleArray::class to DoubleArraySerializer(),
+    Float::class to Float.serializer(),
+    FloatArray::class to FloatArraySerializer(),
+    Long::class to Long.serializer(),
+    LongArray::class to LongArraySerializer(),
+    ULong::class to ULong.serializer(),
+    ULongArray::class to ULongArraySerializer(),
+    Int::class to Int.serializer(),
+    IntArray::class to IntArraySerializer(),
+    UInt::class to UInt.serializer(),
+    UIntArray::class to UIntArraySerializer(),
+    Short::class to Short.serializer(),
+    ShortArray::class to ShortArraySerializer(),
+    UShort::class to UShort.serializer(),
+    UShortArray::class to UShortArraySerializer(),
+    Byte::class to Byte.serializer(),
+    ByteArray::class to ByteArraySerializer(),
+    UByte::class to UByte.serializer(),
+    UByteArray::class to UByteArraySerializer(),
+    Boolean::class to Boolean.serializer(),
+    BooleanArray::class to BooleanArraySerializer(),
+    Unit::class to Unit.serializer(),
+    Nothing::class to NothingSerializer(),
+    Duration::class to Duration.serializer(),
+    Uuid::class to Uuid.serializer()
+)
diff --git a/core/jvmMain/src/kotlinx/serialization/internal/Platform.kt b/core/jvmMain/src/kotlinx/serialization/internal/Platform.kt
index 5cf32d0e5d..b838a0fe52 100644
--- a/core/jvmMain/src/kotlinx/serialization/internal/Platform.kt
+++ b/core/jvmMain/src/kotlinx/serialization/internal/Platform.kt
@@ -5,8 +5,11 @@
 package kotlinx.serialization.internal
 
 import kotlinx.serialization.*
+import kotlinx.serialization.builtins.*
 import java.lang.reflect.*
 import kotlin.reflect.*
+import kotlin.time.*
+import kotlin.uuid.*
 
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun <T> Array<T>.getChecked(index: Int): T {
@@ -158,3 +161,53 @@ private fun <T : Any> Class<T>.findObjectSerializer(): KSerializer<T>? {
 }
 
 internal actual fun isReferenceArray(rootClass: KClass<Any>): Boolean = rootClass.java.isArray
+
+@OptIn(ExperimentalSerializationApi::class)
+internal actual fun initBuiltins(): Map<KClass<*>, KSerializer<*>> = buildMap {
+    // Standard classes are always present
+    put(String::class, String.serializer())
+    put(Char::class, Char.serializer())
+    put(CharArray::class, CharArraySerializer())
+    put(Double::class, Double.serializer())
+    put(DoubleArray::class, DoubleArraySerializer())
+    put(Float::class, Float.serializer())
+    put(FloatArray::class, FloatArraySerializer())
+    put(Long::class, Long.serializer())
+    put(LongArray::class, LongArraySerializer())
+    put(ULong::class, ULong.serializer())
+    put(Int::class, Int.serializer())
+    put(IntArray::class, IntArraySerializer())
+    put(UInt::class, UInt.serializer())
+    put(Short::class, Short.serializer())
+    put(ShortArray::class, ShortArraySerializer())
+    put(UShort::class, UShort.serializer())
+    put(Byte::class, Byte.serializer())
+    put(ByteArray::class, ByteArraySerializer())
+    put(UByte::class, UByte.serializer())
+    put(Boolean::class, Boolean.serializer())
+    put(BooleanArray::class, BooleanArraySerializer())
+    put(Unit::class, Unit.serializer())
+    put(Nothing::class, NothingSerializer())
+
+    // Duration is a stable class, but may be missing in very old stdlibs
+    loadSafe { put(Duration::class, Duration.serializer()) }
+
+    // Experimental types that may be missing
+    @OptIn(ExperimentalUnsignedTypes::class) run {
+        loadSafe { put(ULongArray::class, ULongArraySerializer()) }
+        loadSafe { put(UIntArray::class, UIntArraySerializer()) }
+        loadSafe { put(UShortArray::class, UShortArraySerializer()) }
+        loadSafe { put(UByteArray::class, UByteArraySerializer()) }
+    }
+    @OptIn(ExperimentalUuidApi::class)
+    loadSafe { put(Uuid::class, Uuid.serializer()) }
+}
+
+// Reference classes in [block] ignoring any exceptions related to class loading
+private inline fun loadSafe(block: () -> Unit) {
+    try {
+        block()
+    } catch (_: NoClassDefFoundError) {
+    } catch (_: ClassNotFoundException) {
+    }
+}
diff --git a/core/nativeMain/src/kotlinx/serialization/internal/Platform.kt b/core/nativeMain/src/kotlinx/serialization/internal/Platform.kt
index ddf690c25c..c2e9fdd7e0 100644
--- a/core/nativeMain/src/kotlinx/serialization/internal/Platform.kt
+++ b/core/nativeMain/src/kotlinx/serialization/internal/Platform.kt
@@ -5,7 +5,10 @@
 package kotlinx.serialization.internal
 
 import kotlinx.serialization.*
+import kotlinx.serialization.builtins.*
 import kotlin.reflect.*
+import kotlin.time.*
+import kotlin.uuid.*
 
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun <T> Array<T>.getChecked(index: Int): T {
@@ -71,3 +74,36 @@ internal actual fun <T : Any, E : T?> ArrayList<E>.toNativeArrayImpl(eClass: KCl
 private fun <T> arrayOfAnyNulls(size: Int): Array<T> = arrayOfNulls<Any>(size) as Array<T>
 
 internal actual fun isReferenceArray(rootClass: KClass<Any>): Boolean = rootClass == Array::class
+
+@OptIn(ExperimentalUnsignedTypes::class, ExperimentalUuidApi::class, ExperimentalSerializationApi::class)
+internal actual fun initBuiltins(): Map<KClass<*>, KSerializer<*>> = mapOf(
+    String::class to String.serializer(),
+    Char::class to Char.serializer(),
+    CharArray::class to CharArraySerializer(),
+    Double::class to Double.serializer(),
+    DoubleArray::class to DoubleArraySerializer(),
+    Float::class to Float.serializer(),
+    FloatArray::class to FloatArraySerializer(),
+    Long::class to Long.serializer(),
+    LongArray::class to LongArraySerializer(),
+    ULong::class to ULong.serializer(),
+    ULongArray::class to ULongArraySerializer(),
+    Int::class to Int.serializer(),
+    IntArray::class to IntArraySerializer(),
+    UInt::class to UInt.serializer(),
+    UIntArray::class to UIntArraySerializer(),
+    Short::class to Short.serializer(),
+    ShortArray::class to ShortArraySerializer(),
+    UShort::class to UShort.serializer(),
+    UShortArray::class to UShortArraySerializer(),
+    Byte::class to Byte.serializer(),
+    ByteArray::class to ByteArraySerializer(),
+    UByte::class to UByte.serializer(),
+    UByteArray::class to UByteArraySerializer(),
+    Boolean::class to Boolean.serializer(),
+    BooleanArray::class to BooleanArraySerializer(),
+    Unit::class to Unit.serializer(),
+    Nothing::class to NothingSerializer(),
+    Duration::class to Duration.serializer(),
+    Uuid::class to Uuid.serializer()
+)
diff --git a/core/wasmMain/src/kotlinx/serialization/internal/Platform.kt b/core/wasmMain/src/kotlinx/serialization/internal/Platform.kt
index 146845be3a..ecfee8ede8 100644
--- a/core/wasmMain/src/kotlinx/serialization/internal/Platform.kt
+++ b/core/wasmMain/src/kotlinx/serialization/internal/Platform.kt
@@ -5,7 +5,10 @@
 package kotlinx.serialization.internal
 
 import kotlinx.serialization.*
+import kotlinx.serialization.builtins.*
 import kotlin.reflect.*
+import kotlin.time.*
+import kotlin.uuid.*
 
 @Suppress("NOTHING_TO_INLINE")
 internal actual inline fun <T> Array<T>.getChecked(index: Int): T {
@@ -61,3 +64,36 @@ internal actual fun <T> createParametrizedCache(factory: (KClass<Any>, List<KTyp
 internal actual fun <T : Any, E : T?> ArrayList<E>.toNativeArrayImpl(eClass: KClass<T>): Array<E> = toTypedArray()
 
 internal actual fun isReferenceArray(rootClass: KClass<Any>): Boolean = rootClass == Array::class
+
+@OptIn(ExperimentalUnsignedTypes::class, ExperimentalUuidApi::class, ExperimentalSerializationApi::class)
+internal actual fun initBuiltins(): Map<KClass<*>, KSerializer<*>> = mapOf(
+    String::class to String.serializer(),
+    Char::class to Char.serializer(),
+    CharArray::class to CharArraySerializer(),
+    Double::class to Double.serializer(),
+    DoubleArray::class to DoubleArraySerializer(),
+    Float::class to Float.serializer(),
+    FloatArray::class to FloatArraySerializer(),
+    Long::class to Long.serializer(),
+    LongArray::class to LongArraySerializer(),
+    ULong::class to ULong.serializer(),
+    ULongArray::class to ULongArraySerializer(),
+    Int::class to Int.serializer(),
+    IntArray::class to IntArraySerializer(),
+    UInt::class to UInt.serializer(),
+    UIntArray::class to UIntArraySerializer(),
+    Short::class to Short.serializer(),
+    ShortArray::class to ShortArraySerializer(),
+    UShort::class to UShort.serializer(),
+    UShortArray::class to UShortArraySerializer(),
+    Byte::class to Byte.serializer(),
+    ByteArray::class to ByteArraySerializer(),
+    UByte::class to UByte.serializer(),
+    UByteArray::class to UByteArraySerializer(),
+    Boolean::class to Boolean.serializer(),
+    BooleanArray::class to BooleanArraySerializer(),
+    Unit::class to Unit.serializer(),
+    Nothing::class to NothingSerializer(),
+    Duration::class to Duration.serializer(),
+    Uuid::class to Uuid.serializer()
+)