diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
index 40b9da1cdfc..03118666b62 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
@@ -174,5 +174,7 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
         )
 
     override val valueParameterCheckers: Set<FirValueParameterChecker>
-        get() = setOf()
+        get() = setOf(
+            FirValueParameterDefaultValueTypeMismatchChecker,
+        )
 }
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirValueParameterDefaultValueTypeMismatchChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirValueParameterDefaultValueTypeMismatchChecker.kt
new file mode 100644
index 00000000000..57a956102e1
--- /dev/null
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirValueParameterDefaultValueTypeMismatchChecker.kt
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2010-2023 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.fir.analysis.checkers.declaration
+
+import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.fir.analysis.checkers.checkTypeMismatch
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.declarations.FirValueParameter
+import org.jetbrains.kotlin.fir.types.coneType
+
+object FirValueParameterDefaultValueTypeMismatchChecker : FirValueParameterChecker() {
+    override fun check(declaration: FirValueParameter, context: CheckerContext, reporter: DiagnosticReporter) {
+        val defaultValue = declaration.defaultValue ?: return
+        val source = requireNotNull(declaration.source)
+        val parameterType = declaration.returnTypeRef.coneType
+
+        checkTypeMismatch(parameterType, null, defaultValue, context, source, reporter, true)
+    }
+}
\ No newline at end of file
diff --git a/compiler/frontend.common-psi/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt b/compiler/frontend.common-psi/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt
index 91cbee61f7a..2ab47fbcb2a 100644
--- a/compiler/frontend.common-psi/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt
+++ b/compiler/frontend.common-psi/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt
@@ -945,11 +945,14 @@ object PositioningStrategies {
 
     val PROPERTY_INITIALIZER: PositioningStrategy<KtNamedDeclaration> = object : PositioningStrategy<KtNamedDeclaration>() {
         override fun mark(element: KtNamedDeclaration): List<TextRange> {
-            return markElement(when (element) {
-                is KtProperty -> element.initializer ?: element
-                is KtParameter -> element.typeReference ?: element
-                else -> element
-            })
+            return markElement(
+                when (element) {
+                    is KtProperty -> element.initializer ?: element
+                    // Type reference is used as a target for loop variable type mismatches
+                    is KtParameter -> element.defaultValue ?: element.typeReference ?: element
+                    else -> element
+                }
+            )
         }
     }
 
diff --git a/compiler/testData/codegen/box/collectionLiterals/defaultAnnotationParameterValues.kt b/compiler/testData/codegen/box/collectionLiterals/defaultAnnotationParameterValues.kt
index f361eb970c7..e926ab15d7f 100644
--- a/compiler/testData/codegen/box/collectionLiterals/defaultAnnotationParameterValues.kt
+++ b/compiler/testData/codegen/box/collectionLiterals/defaultAnnotationParameterValues.kt
@@ -19,6 +19,7 @@ annotation class Foo(
         val a: IntArray = [],
         val b: IntArray = [1, 2, 3],
         val c: Array<String> = ["/"],
+        @Suppress("INITIALIZER_TYPE_MISMATCH") // Remove after KT-59581 is fixed
         val d: Array<KClass<*>> = [Int::class, Array<Int>::class],
         val e: DoubleArray = [1.0]
 )
diff --git a/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt b/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt
index 359e3ced476..1b132bd636a 100644
--- a/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt
+++ b/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt
@@ -1,6 +1,6 @@
 val x = ""
 
-fun bar(x : Int = "", y : Int = x, z : String = y) {
+fun bar(x : Int = <!INITIALIZER_TYPE_MISMATCH!>""<!>, y : Int = x, z : String = <!INITIALIZER_TYPE_MISMATCH!>y<!>) {
 
 }
 
@@ -8,7 +8,7 @@ fun bar(x : Int = "", y : Int = x, z : String = y) {
 
 class A(x : Int = <!UNINITIALIZED_PARAMETER!>y<!>, y : Int = x) { // None of the references is resolved, no types checked
     constructor(x : Int = <!UNINITIALIZED_PARAMETER!>x<!>) : this(x, x)
-    fun foo(bool: Boolean, a: Int = <!UNINITIALIZED_PARAMETER!>b<!>, b: String = a) {}
+    fun foo(bool: Boolean, a: Int = <!INITIALIZER_TYPE_MISMATCH, UNINITIALIZED_PARAMETER!>b<!>, b: String = <!INITIALIZER_TYPE_MISMATCH!>a<!>) {}
 }
 
 val z = 3
diff --git a/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt b/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt
index af504b4e89b..eecd840b0cd 100644
--- a/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt
+++ b/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt
@@ -1,11 +1,11 @@
 object A1<!CONSTRUCTOR_IN_OBJECT!>()<!> {
-    <!CONSTRUCTOR_IN_OBJECT!>constructor(x: Int = "", y: Int)<!> : <!UNRESOLVED_REFERENCE!>this<!>() {
+    <!CONSTRUCTOR_IN_OBJECT!>constructor(x: Int = <!INITIALIZER_TYPE_MISMATCH!>""<!>, y: Int)<!> : <!UNRESOLVED_REFERENCE!>this<!>() {
         x + y
     }
 }
 
 object A2 public <!CONSTRUCTOR_IN_OBJECT!>constructor(private val prop: Int)<!> {
-    <!CONSTRUCTOR_IN_OBJECT!>constructor(x: Int = "", y: Int)<!> : <!NONE_APPLICABLE!>this<!>(x * y) {
+    <!CONSTRUCTOR_IN_OBJECT!>constructor(x: Int = <!INITIALIZER_TYPE_MISMATCH!>""<!>, y: Int)<!> : <!NONE_APPLICABLE!>this<!>(x * y) {
         x + y
     }
 }
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt
index 195a73585a7..7a695277178 100644
--- a/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt
@@ -8,7 +8,7 @@ annotation class Ann4(vararg val a: String = ["/"])
 annotation class Ann5(vararg val a: Ann4 = [])
 annotation class Ann6(vararg val a: Ann4 = [Ann4(*["a", "b"])])
 
-annotation class Ann7(vararg val a: Long = [1L, null, ""])
+annotation class Ann7(vararg val a: Long = <!INITIALIZER_TYPE_MISMATCH!>[1L, null, ""]<!>)
 
 @Ann1(*[])
 fun test1_0() {}
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt
index 2defd97549b..bae77f603bf 100644
--- a/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt
@@ -5,9 +5,9 @@ annotation class Foo(
 )
 
 annotation class Bar(
-        val a: Array<String> = [' '],
+        val a: Array<String> = <!INITIALIZER_TYPE_MISMATCH!>[' ']<!>,
         val b: Array<String> = ["", <!EMPTY_CHARACTER_LITERAL!>''<!>],
-        val c: Array<String> = [1]
+        val c: Array<String> = <!INITIALIZER_TYPE_MISMATCH!>[1]<!>
 )
 
 annotation class Base(
@@ -18,6 +18,6 @@ annotation class Base(
 )
 
 annotation class Err(
-        val a: IntArray = [1L],
-        val b: Array<String> = [1]
+        val a: IntArray = <!INITIALIZER_TYPE_MISMATCH!>[1L]<!>,
+        val b: Array<String> = <!INITIALIZER_TYPE_MISMATCH!>[1]<!>
 )
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt
index 6112f79db2b..06164f377f7 100644
--- a/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt
@@ -17,7 +17,7 @@ annotation class Bar(
 )
 
 annotation class Baz(
-        val a: IntArray = [null],
-        val b: IntArray = [1, null, 2],
-        val c: IntArray = [<!NO_THIS!>this<!>]
+        val a: IntArray = <!INITIALIZER_TYPE_MISMATCH!>[null]<!>,
+        val b: IntArray = <!INITIALIZER_TYPE_MISMATCH!>[1, null, 2]<!>,
+        val c: IntArray = <!INITIALIZER_TYPE_MISMATCH!>[<!NO_THIS!>this<!>]<!>
 )
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt
index 328e56c4402..c3c3b9916a4 100644
--- a/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt
+++ b/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt
@@ -1,2 +1,2 @@
-annotation class A(val a: IntArray = <!TYPE_MISMATCH!>arrayOf(1)<!>)
+annotation class A(val a: IntArray = <!INITIALIZER_TYPE_MISMATCH, TYPE_MISMATCH!>arrayOf(1)<!>)
 annotation class B(val a: IntArray = intArrayOf(1))
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.fir.kt
new file mode 100644
index 00000000000..5ecb7c5b663
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.fir.kt
@@ -0,0 +1,88 @@
+// MODULE: m1-common
+// FILE: common.kt
+
+import kotlin.reflect.KClass
+
+expect annotation class Primitives(
+    val z: Boolean = true,
+    val c: Char = 'c',
+    val b: Byte = 42.toByte(),
+    val s: Short = (-1).toShort(),
+    val i: Int = -42,
+    val f: Float = 2.72f,
+    val j: Long = 123456789123456789L,
+    val d: Double = 3.14159265358979
+)
+
+expect annotation class PrimitiveArrays(
+    val z: BooleanArray = [true],
+    val c: CharArray = ['c'],
+    val b: ByteArray = [42.toByte()],
+    val s: ShortArray = [(-1).toShort()],
+    val i: IntArray = [-42],
+    val f: FloatArray = [2.72f],
+    val j: LongArray = [123456789123456789L],
+    val d: DoubleArray = [3.14159265358979]
+)
+
+enum class En { A, B }
+
+annotation class Anno(val value: String = "Anno")
+
+expect annotation class Classes(
+    val s: String = "OK",
+    val e: En = En.B,
+    // TODO: this does not work at the moment because AnnotationDescriptor subclasses do not implement equals correctly
+    // val a: Anno = Anno(),
+    val k: KClass<*> = List::class
+)
+
+expect annotation class ClassArrays(
+    val s: Array<String> = ["OK"],
+    val e: Array<En> = [En.B],
+    // val a: Array<Anno> = [Anno()],
+    val k: Array<KClass<*>> = <!INITIALIZER_TYPE_MISMATCH!>[List::class]<!>, // KT-59581
+    vararg val v: Int = [42]
+)
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+
+import kotlin.reflect.KClass
+
+actual annotation class Primitives(
+    actual val z: Boolean = true,
+    actual val c: Char = 'c',
+    actual val b: Byte = 42.toByte(),
+    actual val s: Short = (-1).toShort(),
+    actual val i: Int = -42,
+    actual val f: Float = 2.72f,
+    actual val j: Long = 123456789123456789L,
+    actual val d: Double = 3.14159265358979
+)
+
+actual annotation class PrimitiveArrays(
+    actual val z: BooleanArray = [true],
+    actual val c: CharArray = ['c'],
+    actual val b: ByteArray = [42.toByte()],
+    actual val s: ShortArray = [(-1).toShort()],
+    actual val i: IntArray = [-42],
+    actual val f: FloatArray = [2.72f],
+    actual val j: LongArray = [123456789123456789L],
+    actual val d: DoubleArray = [3.14159265358979]
+)
+
+actual annotation class Classes(
+    actual val s: String = "OK",
+    actual val e: En = En.B,
+    // actual val a: Anno = Anno(),
+    actual val k: KClass<*> = List::class
+)
+
+actual annotation class ClassArrays(
+    actual val s: Array<String> = ["OK"],
+    actual val e: Array<En> = [En.B],
+    // actual val a: Array<Anno> = [Anno()],
+    actual val k: Array<KClass<*>> = <!INITIALIZER_TYPE_MISMATCH!>[List::class]<!>,
+    actual vararg val v: Int = [42]
+)
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.kt
index 3fe9dc4930a..ec90c26cbd9 100644
--- a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.kt
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.kt
@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // MODULE: m1-common
 // FILE: common.kt
 
@@ -42,7 +41,7 @@ expect annotation class ClassArrays(
     val s: Array<String> = ["OK"],
     val e: Array<En> = [En.B],
     // val a: Array<Anno> = [Anno()],
-    val k: Array<KClass<*>> = [List::class],
+    val k: Array<KClass<*>> = [List::class], // KT-59581
     vararg val v: Int = [42]
 )
 
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt
index 9c884b34a28..5a73a51460d 100644
--- a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt
@@ -21,7 +21,7 @@ fun test() {
     // platform type with no annotation
     val platformJ = J.staticJ
 
-    fun foo(p: J = platformNN, p1: J = platformN, p2: J = platformJ) {}
+    fun foo(p: J = platformNN, p1: J = <!INITIALIZER_TYPE_MISMATCH!>platformN<!>, p2: J = platformJ) {}
 
     fun foo1(p: J? = platformNN, p1: J? = platformN, p2: J? = platformJ) {}
 }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt
index 1031447dae2..ddbcabbdc0d 100644
--- a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt
@@ -3,6 +3,6 @@ open class B(x: Int) {
     fun foo() = 1
 }
 class A : B {
-    constructor(x: Int, y: Int = <!TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>foo<!>() <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.foo() + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.foo()<!>) :
+    constructor(x: Int, y: Int = <!INITIALIZER_TYPE_MISMATCH, TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>foo<!>() <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.foo() + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.foo()<!>) :
         super(<!ARGUMENT_TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>foo<!>() <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.foo() + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.foo()<!>)
 }
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt
index 43e6380b81a..599982ac729 100644
--- a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt
@@ -4,6 +4,6 @@ open class B(x: Int) {
 }
 class A : B {
     override fun foo() = 2
-    constructor(x: Int, y: Int = <!TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>foo<!>() <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.foo() + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.foo()<!>) :
+    constructor(x: Int, y: Int = <!INITIALIZER_TYPE_MISMATCH, TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>foo<!>() <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.foo() + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.foo()<!>) :
         super(<!ARGUMENT_TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>foo<!>() <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.foo() + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.foo()<!>)
 }
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt
index dbfc4346104..d44bce3b7fa 100644
--- a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt
@@ -1,6 +1,6 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 open class B(val prop: Int)
 class A : B {
-    constructor(x: Int, y: Int = <!TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>prop<!> <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.prop + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.prop<!>) :
+    constructor(x: Int, y: Int = <!INITIALIZER_TYPE_MISMATCH, TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>prop<!> <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.prop + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.prop<!>) :
         super(<!ARGUMENT_TYPE_MISMATCH!>x + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>prop<!> <!OVERLOAD_RESOLUTION_AMBIGUITY!>+<!> <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>this<!>.prop + <!INSTANCE_ACCESS_BEFORE_SUPER_CALL!>super<!>.prop<!>)
 }
diff --git a/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.1.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.1.fir.kt
index 0e3a24eec72..9d9eaf06e05 100644
--- a/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.1.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.1.fir.kt
@@ -65,4 +65,4 @@ fun case_10(x: Int?) {
 }
 
 // TESTCASE NUMBER: 11
-fun case_11(x: Int?, y: Int = x) = null
+fun case_11(x: Int?, y: Int = <!INITIALIZER_TYPE_MISMATCH!>x<!>) = null
diff --git a/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.2.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.2.fir.kt
index 8d43eef7069..964194db0c3 100644
--- a/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.2.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.2.fir.kt
@@ -11,29 +11,29 @@
  */
 
 // TESTCASE NUMBER: 1
-fun case_1(x: Int = null) {
+fun case_1(x: Int = <!NULL_FOR_NONNULL_TYPE!>null<!>) {
     println(x)
 }
 
 // TESTCASE NUMBER: 2
-fun case_2(x: Any = null) {
+fun case_2(x: Any = <!NULL_FOR_NONNULL_TYPE!>null<!>) {
     println(x)
 }
 
 // TESTCASE NUMBER: 3
-fun case_3(x: Nothing = null) {
+fun case_3(x: Nothing = <!NULL_FOR_NONNULL_TYPE!>null<!>) {
     <!OVERLOAD_RESOLUTION_AMBIGUITY!>println<!>(x)
 }
 
 // TESTCASE NUMBER: 4
-class Case4(x: Int = null)
+class Case4(x: Int = <!NULL_FOR_NONNULL_TYPE!>null<!>)
 
 // TESTCASE NUMBER: 5
-class Case5 constructor(x: Any = null)
+class Case5 constructor(x: Any = <!NULL_FOR_NONNULL_TYPE!>null<!>)
 
 // TESTCASE NUMBER: 6
 class Case6 {
-    fun foo(x: Nothing = null) {}
+    fun foo(x: Nothing = <!NULL_FOR_NONNULL_TYPE!>null<!>) {}
 }
 
 // TESTCASE NUMBER: 7
diff --git a/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.3.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.3.fir.kt
index 8129b33c32a..6bc3a711f15 100644
--- a/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.3.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/linked/type-system/introduction-1/p-6/neg/2.3.fir.kt
@@ -11,28 +11,28 @@
  */
 
 // TESTCASE NUMBER: 1
-fun <T: Any> case_1(x: T = null) {
+fun <T: Any> case_1(x: T = <!NULL_FOR_NONNULL_TYPE!>null<!>) {
     println(x)
 }
 
 // TESTCASE NUMBER: 2
-fun <T: K, K: Number> case_2(x: T = null) {
+fun <T: K, K: Number> case_2(x: T = <!NULL_FOR_NONNULL_TYPE!>null<!>) {
     println(x)
 }
 
 // TESTCASE NUMBER: 3
 fun <K: Number> case_3() {
-    class Case4<T: K> (x: T = null)
+    class Case4<T: K> (x: T = <!NULL_FOR_NONNULL_TYPE!>null<!>)
 }
 
 // TESTCASE NUMBER: 4
 fun <T> case_4() {
-    class Case4(x: T = null)
+    class Case4(x: T = <!NULL_FOR_NONNULL_TYPE!>null<!>)
 }
 
 // TESTCASE NUMBER: 5
 fun <T, K> case_5(x: T) where T: Number?, K: Number {
     if (x == null) {
-        class Case5 constructor(y: K = x)
+        class Case5 constructor(y: K = <!INITIALIZER_TYPE_MISMATCH!>x<!>)
     }
 }