diff --git a/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/CreateInstance.kt b/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/CreateInstance.kt
index 72ceb6af..4897ec27 100644
--- a/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/CreateInstance.kt
+++ b/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/CreateInstance.kt
@@ -64,15 +64,31 @@ inline fun <reified T : Any> createInstance() = createInstance(T::class)
 
 @Suppress("UNCHECKED_CAST")
 fun <T : Any> createInstance(kClass: KClass<T>): T {
+    var cause: Throwable? = null
     return MockitoKotlin.instanceCreator(kClass)?.invoke() as T? ?:
-            when {
-                kClass.hasObjectInstance() -> kClass.objectInstance!!
-                kClass.isPrimitive() -> kClass.toDefaultPrimitiveValue()
-                kClass.isMockable() -> kClass.java.uncheckedMock()
-                kClass.isEnum() -> kClass.java.enumConstants.first()
-                kClass.isArray() -> kClass.toArrayInstance()
-                kClass.isClassObject() -> kClass.toClassObject()
-                else -> kClass.easiestConstructor().newInstance()
+            try {
+                when {
+                    kClass.hasObjectInstance() -> kClass.objectInstance!!
+                    kClass.isPrimitive() -> kClass.toDefaultPrimitiveValue()
+                    kClass.isEnum() -> kClass.java.enumConstants.first()
+                    kClass.isArray() -> kClass.toArrayInstance()
+                    kClass.isClassObject() -> kClass.toClassObject()
+                    kClass.isMockable() -> try {
+                        kClass.java.uncheckedMock()
+                    } catch(e: Throwable) {
+                        cause = e
+                        kClass.easiestConstructor().newInstance()
+                    }
+                    else -> kClass.easiestConstructor().newInstance()
+                }
+            } catch(e: Exception) {
+                if (e is MockitoKotlinException) throw e
+
+                cause?.let {
+                    @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
+                    (e as java.lang.Throwable).initCause(it)
+                }
+                throw MockitoKotlinException("Could not create an instance for $kClass.", e)
             }
 }
 
diff --git a/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/Mockito.kt b/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/Mockito.kt
index 0b326997..fc698255 100644
--- a/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/Mockito.kt
+++ b/mockito-kotlin/src/main/kotlin/com/nhaarman/mockito_kotlin/Mockito.kt
@@ -94,7 +94,7 @@ inline fun <reified T : Any> mock(stubbing: KStubbing<T>.(T) -> Unit): T {
 class KStubbing<out T>(private val mock: T) {
     fun <R> on(methodCall: R) = Mockito.`when`(methodCall)
 
-    fun <R : Any> on(methodCall: T.() -> R, c: KClass<R>): OngoingStubbing<R> {
+    fun <R : Any> onGeneric(methodCall: T.() -> R, c: KClass<R>): OngoingStubbing<R> {
         val r = try {
             mock.methodCall()
         } catch(e: NullPointerException) {
@@ -108,8 +108,16 @@ class KStubbing<out T>(private val mock: T) {
         return Mockito.`when`(r)
     }
 
-    inline fun <reified R : Any> on(noinline methodCall: T.() -> R): OngoingStubbing<R> {
-        return on(methodCall, R::class)
+    inline fun <reified R : Any> onGeneric(noinline methodCall: T.() -> R): OngoingStubbing<R> {
+        return onGeneric(methodCall, R::class)
+    }
+
+    fun <R> on(methodCall: T.() -> R): OngoingStubbing<R> {
+        return try {
+            Mockito.`when`(mock.methodCall())
+        } catch(e: NullPointerException) {
+            throw MockitoKotlinException("NullPointerException thrown when stubbing. If you are trying to stub a generic method, try `onGeneric` instead.", e)
+        }
     }
 }
 
diff --git a/mockito-kotlin/src/test/kotlin/Classes.kt b/mockito-kotlin/src/test/kotlin/Classes.kt
index faa67453..71923006 100644
--- a/mockito-kotlin/src/test/kotlin/Classes.kt
+++ b/mockito-kotlin/src/test/kotlin/Classes.kt
@@ -54,6 +54,7 @@ interface Methods {
     fun nullableString(s: String?)
 
     fun stringResult(): String
+    fun nullableStringResult(): String?
     fun builderMethod(): Methods
 }
 
diff --git a/mockito-kotlin/src/test/kotlin/CreateInstanceTest.kt b/mockito-kotlin/src/test/kotlin/CreateInstanceTest.kt
index 991bf735..2fc7e657 100644
--- a/mockito-kotlin/src/test/kotlin/CreateInstanceTest.kt
+++ b/mockito-kotlin/src/test/kotlin/CreateInstanceTest.kt
@@ -476,6 +476,24 @@ class CreateInstanceTest {
         expect(result.second).toBe(2)
     }
 
+    @Test
+    fun sealedClass() {
+        /* When */
+        val result = createInstance(MySealedClass::class)
+
+        /* Then */
+        expect(result).toNotBeNull()
+    }
+
+    @Test
+    fun sealedClassMember() {
+        /* When */
+        val result = createInstance(MySealedClass.MySealedClassMember::class)
+
+        /* Then */
+        expect(result).toNotBeNull()
+    }
+
     private class PrivateClass private constructor(val data: String)
 
     class ClosedClass
@@ -537,4 +555,8 @@ class CreateInstanceTest {
     }
 
     enum class MyEnum { VALUE, ANOTHER_VALUE }
+
+    sealed class MySealedClass {
+        class MySealedClassMember : MySealedClass()
+    }
 }
diff --git a/mockito-kotlin/src/test/kotlin/MockitoTest.kt b/mockito-kotlin/src/test/kotlin/MockitoTest.kt
index 3db6f1b8..b32355f1 100644
--- a/mockito-kotlin/src/test/kotlin/MockitoTest.kt
+++ b/mockito-kotlin/src/test/kotlin/MockitoTest.kt
@@ -351,6 +351,20 @@ class MockitoTest {
         expect(result).toBeTheSameAs(mock)
     }
 
+    @Test
+    fun testMockStubbing_nullable() {
+        /* Given */
+        val mock = mock<Methods> {
+            on { nullableStringResult() } doReturn "Test"
+        }
+
+        /* When */
+        val result = mock.nullableStringResult()
+
+        /* Then */
+        expect(result).toBe("Test")
+    }
+
     @Test
     fun testMockStubbing_doThrow() {
         /* Given */
@@ -438,10 +452,22 @@ class MockitoTest {
     }
 
     @Test
-    fun doReturn_withGenericIntReturnType() {
+    fun doReturn_withGenericIntReturnType_on() {
+        /* Expect */
+        expectErrorWithMessage("onGeneric") on {
+
+            /* When */
+            mock<GenericMethods<Int>> {
+                on { genericMethod() } doReturn 2
+            }
+        }
+    }
+
+    @Test
+    fun doReturn_withGenericIntReturnType_onGeneric() {
         /* Given */
         val mock = mock<GenericMethods<Int>> {
-            on { genericMethod() } doReturn 2
+            onGeneric { genericMethod() } doReturn 2
         }
 
         /* Then */
diff --git a/mockito-kotlin/src/testInlineMockito/kotlin/CreateInstanceInlineTest.kt b/mockito-kotlin/src/testInlineMockito/kotlin/CreateInstanceInlineTest.kt
index 47e35211..e7cf038a 100644
--- a/mockito-kotlin/src/testInlineMockito/kotlin/CreateInstanceInlineTest.kt
+++ b/mockito-kotlin/src/testInlineMockito/kotlin/CreateInstanceInlineTest.kt
@@ -23,6 +23,7 @@
  */
 
 import com.nhaarman.expect.expect
+import com.nhaarman.expect.expectErrorWithMessage
 import com.nhaarman.mockito_kotlin.*
 import org.junit.Test
 import java.io.IOException
@@ -105,7 +106,7 @@ class CreateInstanceInlineTest {
         /* Then */
         expect(i).toBe(0)
     }
-    
+
     @Test
     fun createStringInstance() {
         /* When */
@@ -115,10 +116,33 @@ class CreateInstanceInlineTest {
         expect(s).toBe("")
     }
 
+    @Test
+    fun sealedClass_fails() {
+        /* Expect */
+        expectErrorWithMessage("Could not create") on {
+
+            /* When */
+            createInstance(MySealedClass::class)
+        }
+    }
+
+    @Test
+    fun sealedClassMember() {
+        /* When */
+        val result = createInstance(MySealedClass.MySealedClassMember::class)
+
+        /* Then */
+        expect(result).toNotBeNull()
+    }
+
     interface Methods {
 
         fun throwableClass(t: ThrowableClass)
     }
 
     class ThrowableClass(cause: Throwable) : Throwable(cause)
+
+    sealed class MySealedClass {
+        class MySealedClassMember : MySealedClass()
+    }
 }