diff --git a/core/runtime.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt b/core/runtime.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt
index d13dd573029..adf795c49ce 100644
--- a/core/runtime.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt
+++ b/core/runtime.jvm/src/kotlin/reflect/jvm/internal/foreignKClasses.kt
@@ -24,7 +24,7 @@ import kotlin.reflect.jvm.internal.pcollections.HashPMap
 // Arrays are needed because the same class can be loaded by different class loaders, which results in different Class instances.
 // This variable is not volatile intentionally: we don't care if there's a data race on it and some KClass instances will be lost.
 // We do care however about general performance on read access to it, thus no synchronization is done here whatsoever
-private var FOREIGN_K_CLASSES = HashPMap.empty<String, Any>()!!
+private var FOREIGN_K_CLASSES = HashPMap.empty<String, Any>()
 
 // This function is invoked on each reflection access to Java classes, properties, etc. Performance is critical here.
 fun <T> foreignKotlinClass(jClass: Class<T>): KClassImpl<T> {
@@ -55,11 +55,11 @@ fun <T> foreignKotlinClass(jClass: Class<T>): KClassImpl<T> {
         System.arraycopy(cached, 0, newArray, 0, size)
         val newKClass = KClassImpl<T>(jClass)
         newArray[size] = WeakReference(newKClass)
-        FOREIGN_K_CLASSES = FOREIGN_K_CLASSES.plus(name, newArray)!!
+        FOREIGN_K_CLASSES = FOREIGN_K_CLASSES.plus(name, newArray)
         return newKClass
     }
 
     val newKClass = KClassImpl<T>(jClass)
-    FOREIGN_K_CLASSES = FOREIGN_K_CLASSES.plus(name, WeakReference(newKClass))!!
+    FOREIGN_K_CLASSES = FOREIGN_K_CLASSES.plus(name, WeakReference(newKClass))
     return newKClass
 }
diff --git a/core/runtime.jvm/src/kotlin/reflect/jvm/internal/pcollections/HashPMap.java b/core/runtime.jvm/src/kotlin/reflect/jvm/internal/pcollections/HashPMap.java
index 6909aa304c6..473b2d6d922 100644
--- a/core/runtime.jvm/src/kotlin/reflect/jvm/internal/pcollections/HashPMap.java
+++ b/core/runtime.jvm/src/kotlin/reflect/jvm/internal/pcollections/HashPMap.java
@@ -16,6 +16,8 @@
 
 package kotlin.reflect.jvm.internal.pcollections;
 
+import org.jetbrains.annotations.NotNull;
+
 /**
  * A persistent map from non-null keys to non-null values.
  */
@@ -23,6 +25,7 @@ public final class HashPMap<K, V> {
     private static final HashPMap<Object, Object> EMPTY = new HashPMap<Object, Object>(IntTreePMap.<ConsPStack<MapEntry<Object, Object>>>empty(), 0);
 
     @SuppressWarnings("unchecked")
+    @NotNull
     public static <K, V> HashPMap<K, V> empty() {
         return (HashPMap<K, V>) HashPMap.EMPTY;
     }
@@ -51,6 +54,7 @@ public final class HashPMap<K, V> {
         return null;
     }
 
+    @NotNull
     public HashPMap<K, V> plus(K key, V value) {
         ConsPStack<MapEntry<K, V>> entries = getEntries(key.hashCode());
         int size0 = entries.size();
@@ -60,6 +64,7 @@ public final class HashPMap<K, V> {
         return new HashPMap<K, V>(intMap.plus(key.hashCode(), entries), size - size0 + entries.size());
     }
 
+    @NotNull
     public HashPMap<K, V> minus(Object key) {
         ConsPStack<MapEntry<K, V>> entries = getEntries(key.hashCode());
         int i = keyIndexIn(entries, key);