diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt
index eb25690bac9..7b2f791e11e 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt
@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.ir.backend.js
 
 import org.jetbrains.kotlin.builtins.PrimitiveType
-import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
 import org.jetbrains.kotlin.ir.backend.js.utils.Namer
 import org.jetbrains.kotlin.ir.builders.declarations.addFunction
 import org.jetbrains.kotlin.ir.builders.declarations.addTypeParameter
@@ -21,6 +20,7 @@ import org.jetbrains.kotlin.ir.types.defaultType
 import org.jetbrains.kotlin.ir.types.isLong
 import org.jetbrains.kotlin.ir.util.constructors
 import org.jetbrains.kotlin.ir.util.findDeclaration
+import org.jetbrains.kotlin.ir.util.kotlinPackageFqn
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi2ir.findSingleFunction
@@ -201,6 +201,8 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
     val returnIfSuspended = getInternalFunction("returnIfSuspended")
     val getContinuation = getInternalFunction("getContinuation")
 
+    val jsEnsureNonNull = getFunctionInKotlinPackage("ensureNotNull")
+
     // Arrays:
     val array = context.symbolTable.referenceClass(irBuiltIns.builtIns.array)
 
@@ -282,6 +284,9 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
     private fun getInternalWithoutPackage(name: String) =
         context.symbolTable.referenceSimpleFunction(context.getFunctions(FqName(name)).single())
 
+    private fun getFunctionInKotlinPackage(name: String) =
+        context.symbolTable.referenceSimpleFunction(context.getFunctions(kotlinPackageFqn.child(Name.identifier(name))).single())
+
     private fun getInternalClassWithoutPackage(fqName: String) =
         context.symbolTable.referenceClass(context.getClass(FqName(fqName)))
 
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/calls/ExceptionHelperCallsTransformer.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/calls/ExceptionHelperCallsTransformer.kt
index e8866b11b87..4c5a7a93f75 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/calls/ExceptionHelperCallsTransformer.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/calls/ExceptionHelperCallsTransformer.kt
@@ -14,17 +14,18 @@ import org.jetbrains.kotlin.name.Name
 
 class ExceptionHelperCallsTransformer(private val context: JsIrBackendContext) : CallsTransformer {
 
-    private fun referenceFunction(fqn: FqName) = context.getFunctions(fqn).singleOrNull()?.let {
-        context.symbolTable.referenceSimpleFunction(it)
-    }
+    private fun referenceFunction(fqn: FqName) =
+        context.getFunctions(fqn).singleOrNull()?.let {
+            context.symbolTable.referenceSimpleFunction(it)
+        } ?: throw AssertionError("Function not found: $fqn")
 
     private val helperMapping = mapOf(
-        // context.irBuiltIns.throwNpeSymbol to referenceFunction(kotlinPackageFqn.child(Name.identifier("THROW_NPE"))), -- TODO checkNotNullSymbol
+        context.irBuiltIns.checkNotNullSymbol to referenceFunction(kotlinPackageFqn.child(Name.identifier("ensureNotNull"))),
         context.irBuiltIns.throwCceSymbol to referenceFunction(kotlinPackageFqn.child(Name.identifier("THROW_CCE"))),
         context.irBuiltIns.throwIseSymbol to referenceFunction(kotlinPackageFqn.child(Name.identifier("THROW_ISE"))),
         context.irBuiltIns.noWhenBranchMatchedExceptionSymbol to referenceFunction(kotlinPackageFqn.child(Name.identifier("noWhenBranchMatchedException")))
     )
 
-
-    override fun transformFunctionAccess(call: IrFunctionAccessExpression) = helperMapping[call.symbol]?.let { irCall(call, it) } ?: call
+    override fun transformFunctionAccess(call: IrFunctionAccessExpression) =
+        helperMapping[call.symbol]?.let { irCall(call, it) } ?: call
 }
diff --git a/libraries/stdlib/js-ir/runtime/hacks.kt b/libraries/stdlib/js-ir/runtime/hacks.kt
index 7ccef88974d..0a399dede67 100644
--- a/libraries/stdlib/js-ir/runtime/hacks.kt
+++ b/libraries/stdlib/js-ir/runtime/hacks.kt
@@ -20,4 +20,6 @@ fun THROW_CCE(): Nothing {
 }
 fun THROW_NPE(): Nothing {
     throw NullPointerException()
-}
\ No newline at end of file
+}
+
+fun <T:Any> ensureNotNull(v: T?): T = if (v == null) THROW_NPE() else v
\ No newline at end of file