diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KClassImpl.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KClassImpl.kt
index c97db2f7ad5..01ab78b43f8 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KClassImpl.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KClassImpl.kt
@@ -26,10 +26,10 @@ enum class KClassOrigin {
     FOREIGN
 }
 
-private val KOTLIN_CLASS_ANNOTATION_CLASS = javaClassOf<KotlinClass>()
-private val KOTLIN_SYNTHETIC_CLASS_ANNOTATION_CLASS = javaClassOf<KotlinSyntheticClass>()
+private val KOTLIN_CLASS_ANNOTATION_CLASS = javaClass<KotlinClass>()
+private val KOTLIN_SYNTHETIC_CLASS_ANNOTATION_CLASS = javaClass<KotlinSyntheticClass>()
 
-class KClassImpl<T>(val jClass: Class<T>, isKnownToBeKotlin: Boolean) : KClass<T> {
+class KClassImpl<T>(val jClass: Class<T>, isKnownToBeKotlin: Boolean = false) : KClass<T> {
     // TODO: write metadata to local classes
     private val origin: KClassOrigin =
             if (isKnownToBeKotlin ||
@@ -44,7 +44,7 @@ class KClassImpl<T>(val jClass: Class<T>, isKnownToBeKotlin: Boolean) : KClass<T
             }
 
     fun memberProperty(name: String): KMemberProperty<T, *> =
-            if (origin identityEquals KClassOrigin.KOTLIN) {
+            if (origin === KClassOrigin.KOTLIN) {
                 KMemberPropertyImpl<T, Any>(name, this)
             }
             else {
@@ -52,7 +52,7 @@ class KClassImpl<T>(val jClass: Class<T>, isKnownToBeKotlin: Boolean) : KClass<T
             }
 
     fun mutableMemberProperty(name: String): KMutableMemberProperty<T, *> =
-            if (origin identityEquals KClassOrigin.KOTLIN) {
+            if (origin === KClassOrigin.KOTLIN) {
                 KMutableMemberPropertyImpl<T, Any>(name, this)
             }
             else {
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberFunctionImpl.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberFunctionImpl.kt
index 661b6576468..1c80fb91dd3 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberFunctionImpl.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberFunctionImpl.kt
@@ -19,5 +19,5 @@ package kotlin.reflect.jvm.internal
 import java.io.Serializable
 
 public abstract class KMemberFunctionImpl<in T, out R> : Serializable {
-    override fun toString() = "${(this as Object).getClass().getGenericInterfaces()[0]}"
+    override fun toString() = "${javaClass.getGenericInterfaces().first()}"
 }
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberPropertyImpl.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberPropertyImpl.kt
index edfbb59a03d..93269825fda 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberPropertyImpl.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KMemberPropertyImpl.kt
@@ -75,7 +75,7 @@ class KMutableMemberPropertyImpl<T : Any, R>(
     {
         try {
             val returnType = if (getter != null) getter.getReturnType() else field!!.getType()
-            setter = owner.jClass.getMaybeDeclaredMethod(setterName(name), returnType!!)
+            setter = owner.jClass.getMaybeDeclaredMethod(setterName(name), returnType)
         }
         catch (e: NoSuchMethodException) {
             if (field == null) throw NoSuchPropertyException(e)
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPackageImpl.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPackageImpl.kt
index 3e3323d86e9..df51b69f5af 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPackageImpl.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPackageImpl.kt
@@ -19,7 +19,7 @@ package kotlin.reflect.jvm.internal
 import kotlin.reflect.KPackage
 import kotlin.jvm.internal.KotlinPackage
 
-private val KOTLIN_PACKAGE_ANNOTATION_CLASS = javaClassOf<KotlinPackage>()
+private val KOTLIN_PACKAGE_ANNOTATION_CLASS = javaClass<KotlinPackage>()
 
 class KPackageImpl(val jClass: Class<*>) : KPackage {
     override fun equals(other: Any?): Boolean =
@@ -28,22 +28,11 @@ class KPackageImpl(val jClass: Class<*>) : KPackage {
     override fun hashCode(): Int =
             jClass.hashCode()
 
-    suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
     override fun toString(): String {
-        val name = jClass.getName() as java.lang.String
-        return if (jClass.isAnnotationPresent(KOTLIN_PACKAGE_ANNOTATION_CLASS)) {
-            // Cast to Any is needed to suppress the error: "Operator '==' cannot be applied to 'java.lang.String' and 'kotlin.String'"
-            if ((name : Any) == "_DefaultPackage") {
-                "package <default>"
-            }
-            else {
-                val lastDot = name.lastIndexOf(".")
-                if (lastDot >= 0) {
-                    "package ${name.substring(0, lastDot)}"
-                }
-                else "package $name"
-            }
+        val name = jClass.getName()
+        return "package " + if (jClass.isAnnotationPresent(KOTLIN_PACKAGE_ANNOTATION_CLASS)) {
+            if (name == "_DefaultPackage") "<default>" else name.substringBeforeLast(".")
         }
-        else "package $name"
+        else name
     }
 }
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelExtensionPropertyImpl.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelExtensionPropertyImpl.kt
index 77d40982792..6be866dc6bb 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelExtensionPropertyImpl.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelExtensionPropertyImpl.kt
@@ -60,7 +60,7 @@ class KMutableTopLevelExtensionPropertyImpl<T, R>(
         receiverClass: Class<T>
 ) : KMutableTopLevelExtensionProperty<T, R>, KMutablePropertyImpl<R>, KTopLevelExtensionPropertyImpl<T, R>(name, owner, receiverClass) {
     override val setter: Method = try {
-        owner.jClass.getMethod(setterName(name), receiverClass, getter.getReturnType()!!)
+        owner.jClass.getMethod(setterName(name), receiverClass, getter.getReturnType())
     }
     catch (e: NoSuchMethodException) {
         throw NoSuchPropertyException(e)
@@ -79,9 +79,8 @@ class KMutableTopLevelExtensionPropertyImpl<T, R>(
             "var ${mapJavaClassToKotlin(receiverClass.getName())}.$name"
 }
 
-suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
 private fun mapJavaClassToKotlin(name: String): String {
-    if (Character.isLowerCase(name[0])) {
+    if (name[0].isLowerCase()) {
         return when (name) {
             "boolean" -> "kotlin.Boolean"
             "char" -> "kotlin.Char"
@@ -95,8 +94,8 @@ private fun mapJavaClassToKotlin(name: String): String {
         }
     }
     if (name[0] == '[') {
-        val element = (name as java.lang.String).substring(1) as java.lang.String
-        return when (element.charAt(0)) {
+        val element = name.substring(1)
+        return when (element[0]) {
             'Z' -> "kotlin.BooleanArray"
             'C' -> "kotlin.CharArray"
             'B' -> "kotlin.ByteArray"
@@ -106,7 +105,7 @@ private fun mapJavaClassToKotlin(name: String): String {
             'J' -> "kotlin.LongArray"
             'D' -> "kotlin.DoubleArray"
             'L' -> "kotlin.Array<${mapJavaClassToKotlin(element.substring(1, element.length() - 1))}>"
-            else -> "kotlin.Array<${mapJavaClassToKotlin(element as kotlin.String)}>"
+            else -> "kotlin.Array<${mapJavaClassToKotlin(element)}>"
         }
     }
     return name
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelVariableImpl.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelVariableImpl.kt
index 9feadfc4947..b4d7903d10f 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelVariableImpl.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelVariableImpl.kt
@@ -59,7 +59,7 @@ class KMutableTopLevelVariableImpl<R>(
         owner: KPackageImpl
 ) : KMutableTopLevelVariable<R>, KMutableVariableImpl<R>, KTopLevelVariableImpl<R>(name, owner) {
     override val setter: Method = try {
-        owner.jClass.getMethod(setterName(name), getter.getReturnType()!!)
+        owner.jClass.getMethod(setterName(name), getter.getReturnType())
     }
     catch (e: NoSuchMethodException) {
         throw NoSuchPropertyException(e)
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt
index e8037d40fbf..4830af8131e 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt
@@ -42,7 +42,7 @@ fun <T> foreignKotlinClass(jClass: Class<T>): KClassImpl<T> {
         for (ref in cached) {
             val kClass = ref.get()
             if (kClass?.jClass == jClass) {
-                return kClass!!
+                return kClass
             }
         }
 
@@ -53,13 +53,13 @@ fun <T> foreignKotlinClass(jClass: Class<T>): KClassImpl<T> {
         val newArray = arrayOfNulls<WeakReference<KClassImpl<*>>>(size + 1)
         // Don't use Arrays.copyOf because it works reflectively
         System.arraycopy(cached, 0, newArray, 0, size)
-        val newKClass = KClassImpl(jClass, false)
+        val newKClass = KClassImpl(jClass)
         newArray[size] = WeakReference(newKClass)
         FOREIGN_K_CLASSES = FOREIGN_K_CLASSES.plus(name, newArray)
         return newKClass
     }
 
-    val newKClass = KClassImpl(jClass, false)
+    val newKClass = KClassImpl(jClass)
     FOREIGN_K_CLASSES = FOREIGN_K_CLASSES.plus(name, WeakReference(newKClass))
     return newKClass
 }
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/util.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/util.kt
index 5d658c6ef06..ffa445f2a92 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/internal/util.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/internal/util.kt
@@ -17,29 +17,16 @@
 package kotlin.reflect.jvm.internal
 
 import java.lang.reflect.Method
-import kotlin.jvm.internal.Intrinsic
 
-// TODO: use stdlib?
-suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
 private fun String.capitalizeWithJavaBeanConvention(): String {
-    // The code is a bit crooked because otherwise there are overload resolution ambiguities caused by the fact
-    // that we compile it with the built-ins both in source and as a compiled library
-    val l = length()
-    if (l > 1 && Character.isUpperCase(get(1))) return this
-    val first = get(0)
-    this as java.lang.String
-    return "" + Character.toUpperCase(first) + substring(1, l)
+    if (length() > 1 && Character.isUpperCase(this[1])) return this
+    return Character.toUpperCase(this[0]) + substring(1, length())
 }
 
 private fun getterName(propertyName: String): String = "get" + propertyName.capitalizeWithJavaBeanConvention()
 private fun setterName(propertyName: String): String = "set" + propertyName.capitalizeWithJavaBeanConvention()
 
 
-// A local copy of javaClass() from stdlib is needed because there's no dependency on stdlib in runtime.jvm
-[Intrinsic("kotlin.javaClass.function")]
-fun <reified T> javaClassOf(): Class<T> = throw UnsupportedOperationException()
-
-
 private fun Class<*>.getMaybeDeclaredMethod(name: String, vararg parameterTypes: Class<*>): Method {
     try {
         return getMethod(name, *parameterTypes)
diff --git a/core/reflection.jvm/src/kotlin/reflect/jvm/mapping.kt b/core/reflection.jvm/src/kotlin/reflect/jvm/mapping.kt
index da2bc4efda3..c833c0b8ca0 100644
--- a/core/reflection.jvm/src/kotlin/reflect/jvm/mapping.kt
+++ b/core/reflection.jvm/src/kotlin/reflect/jvm/mapping.kt
@@ -61,7 +61,7 @@ public val KMemberProperty<*, *>.javaField: Field?
 
 // TODO: getstatic $kotlinClass or go to foreignKClasses
 public val <T> Class<T>.kotlin: KClass<T>
-    get() = KClassImpl(this, false)
+    get() = KClassImpl(this)
 
 // TODO: getstatic $kotlinPackage
 public val Class<*>.kotlinPackage: KPackage
@@ -71,7 +71,7 @@ public val Class<*>.kotlinPackage: KPackage
 public val Field.kotlin: KProperty<*>
     get() {
         val clazz = getDeclaringClass()
-        val name = getName()!!
+        val name = getName()
         val modifiers = getModifiers()
         val static = Modifier.isStatic(modifiers)
         val final = Modifier.isFinal(modifiers)
@@ -84,4 +84,3 @@ public val Field.kotlin: KProperty<*>
             return if (final) Reflection.memberProperty(name, kClass) else Reflection.mutableMemberProperty(name, kClass)
         }
     }
-