diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/IrUtils.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/IrUtils.kt
new file mode 100644
index 00000000000..b02c2e80e92
--- /dev/null
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/IrUtils.kt
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.backend.jvm.ir
+
+import org.jetbrains.kotlin.backend.jvm.codegen.isJvmInterface
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrTypeParameter
+import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
+import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.types.classOrNull
+import org.jetbrains.kotlin.ir.types.classifierOrNull
+
+/**
+ * Computes the erased class for this type parameter according to the java erasure rules.
+ */
+val IrTypeParameter.erasedUpperBound: IrClass
+    get() {
+        // Pick the (necessarily unique) non-interface upper bound if it exists
+        for (type in superTypes) {
+            val irClass = type.classOrNull?.owner ?: continue
+            if (!irClass.isJvmInterface) return irClass
+        }
+
+        // Otherwise, choose either the first IrClass supertype or recurse.
+        // In the first case, all supertypes are interface types and the choice was arbitrary.
+        // In the second case, there is only a single supertype.
+        return superTypes.first().erasedUpperBound
+    }
+
+val IrType.erasedUpperBound: IrClass
+    get() = when (val classifier = classifierOrNull) {
+        is IrClassSymbol -> classifier.owner
+        is IrTypeParameterSymbol -> classifier.owner.erasedUpperBound
+        else -> throw IllegalStateException()
+    }
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/BridgeLowering.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/BridgeLowering.kt
index 5642ba42fc4..93331e042ab 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/BridgeLowering.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/BridgeLowering.kt
@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.backend.common.lower.irNot
 import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
 import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
 import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
+import org.jetbrains.kotlin.backend.jvm.ir.erasedUpperBound
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
@@ -30,20 +31,14 @@ import org.jetbrains.kotlin.ir.declarations.impl.IrValueParameterImpl
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrStatementOrigin
 import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
-import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
-import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.symbols.impl.IrSimpleFunctionSymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrValueParameterSymbolImpl
 import org.jetbrains.kotlin.ir.types.IrErrorType
 import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.types.IrType
-import org.jetbrains.kotlin.ir.types.defaultType
 import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
 import org.jetbrains.kotlin.ir.types.impl.IrStarProjectionImpl
-import org.jetbrains.kotlin.ir.util.defaultType
-import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
-import org.jetbrains.kotlin.ir.util.isInterface
-import org.jetbrains.kotlin.ir.util.parentAsClass
+import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 import org.jetbrains.org.objectweb.asm.commons.Method
@@ -278,9 +273,9 @@ private class BridgeLowering(val context: JvmBackendContext) : ClassLoweringPass
                             superQualifierSymbol = if (invokeStatically) maybeOrphanedTarget.parentAsClass.symbol else null
                         ).apply {
                             passTypeArgumentsFrom(this@createBridgeBody)
-                            dispatchReceiver = irImplicitCast(irGet(dispatchReceiverParameter!!), dispatchReceiverParameter!!.type)
+                            dispatchReceiver = irGet(dispatchReceiverParameter!!)
                             extensionReceiverParameter?.let {
-                                extensionReceiver = irImplicitCast(irGet(it), extensionReceiverParameter!!.type)
+                                extensionReceiver = irImplicitCast(irGet(it), maybeOrphanedTarget.extensionReceiverParameter!!.type)
                             }
                             valueParameters.forEach {
                                 putValueArgument(it.index, irImplicitCast(irGet(it), maybeOrphanedTarget.valueParameters[it.index].type))
@@ -341,36 +336,23 @@ private class BridgeLowering(val context: JvmBackendContext) : ClassLoweringPass
     // TODO: should be a type mapper functionality.
     private fun IrType.eraseTypeParameters() = when (this) {
         is IrErrorType -> this
-        is IrSimpleType -> {
-            val owner = classifier.owner
-            when (owner) {
+        is IrSimpleType ->
+            when (val owner = classifier.owner) {
                 is IrClass -> this
                 is IrTypeParameter -> {
-                    val upperBound = owner.upperBoundClass()
+                    val upperBound = owner.erasedUpperBound
                     IrSimpleTypeImpl(
                         upperBound.symbol,
-                        hasQuestionMark,
+                        isNullable(),
                         List(upperBound.typeParameters.size) { IrStarProjectionImpl },    // Should not affect JVM signature, but may result in an invalid type object
                         owner.annotations
                     )
                 }
                 else -> error("Unknown IrSimpleType classifier kind: $owner")
             }
-        }
         else -> error("Unknown IrType kind: $this")
     }
 
-    private fun IrTypeParameter.upperBoundClass(): IrClass {
-        val simpleSuperClassifiers = superTypes.asSequence().filterIsInstance<IrSimpleType>().map { it.classifier }
-        return simpleSuperClassifiers
-                .filterIsInstance<IrClassSymbol>()
-                .let {
-                    it.firstOrNull { !it.owner.isInterface } ?: it.firstOrNull()
-                }?.owner ?:
-            simpleSuperClassifiers.filterIsInstance<IrTypeParameterSymbol>().map { it.owner.upperBoundClass() }.firstOrNull() ?:
-            context.irBuiltIns.anyClass.owner
-    }
-
     private fun IrSimpleFunction.findAllReachableDeclarations() =
         findAllReachableDeclarations(FunctionHandleForIrFunction(this)).map { it.irFunction }