diff --git a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java
index a5d9c90b6f3..8f1f0145f70 100644
--- a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java
+++ b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java
@@ -27486,6 +27486,18 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @Test
+        @TestMetadata("kt49136.kt")
+        public void testKt49136() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt");
+        }
+
+        @Test
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @Test
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/CommonBackendContext.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/CommonBackendContext.kt
index 8593f9b04ac..78cfc46a07e 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/CommonBackendContext.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/CommonBackendContext.kt
@@ -64,4 +64,7 @@ interface CommonBackendContext : BackendContext, LoggingContext {
 
     val optimizeLoopsOverUnsignedArrays: Boolean
         get() = false
+
+    val optimizeNullChecksUsingKotlinNullability: Boolean
+        get() = true
 }
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt
index c0cea9a9d1e..a53d82cd185 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt
@@ -146,9 +146,9 @@ class IfNullExpressionsFusionLowering(val context: CommonBackendContext) : FileL
                 is IrGetClass ->
                     false
                 is IrCall ->
-                    if (!type.isNullable()) false else null
+                    if (context.optimizeNullChecksUsingKotlinNullability && !type.isNullable()) false else null
                 is IrGetField ->
-                    if (!type.isNullable()) false else null
+                    if (context.optimizeNullChecksUsingKotlinNullability && !type.isNullable()) false else null
                 is IrBlock -> {
                     val singleExpr = statements.singleOrNull()
                     if (singleExpr is IrExpression && singleExpr.type == type)
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmBackendContext.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmBackendContext.kt
index a5b53930a3a..bcbdad0d563 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmBackendContext.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmBackendContext.kt
@@ -221,6 +221,9 @@ class JvmBackendContext(
     override val doWhileCounterLoopOrigin: IrStatementOrigin
         get() = JvmLoweredStatementOrigin.DO_WHILE_COUNTER_LOOP
 
+    override val optimizeNullChecksUsingKotlinNullability: Boolean
+        get() = false
+
     inner class JvmIr(
         irModuleFragment: IrModuleFragment,
         symbolTable: SymbolTable
diff --git a/compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt b/compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt
new file mode 100644
index 00000000000..2d546a0417a
--- /dev/null
+++ b/compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt
@@ -0,0 +1,20 @@
+// TARGET_BACKEND: JVM
+// FULL_JDK
+// WITH_REFLECT
+
+class A(val b: B)
+
+class B(val c: String)
+
+fun createByReflection(): A? =
+    A(B("aaa")).apply {
+        val field = javaClass.declaredFields.find { it.name == "b" }!!
+        field.isAccessible = true
+        field.set(this, null)
+    }
+
+fun box(): String {
+    val a = createByReflection()
+    println(a?.b?.c)
+    return "OK"
+}
diff --git a/compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt b/compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt
new file mode 100644
index 00000000000..b34bb2fe1e2
--- /dev/null
+++ b/compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt
@@ -0,0 +1,22 @@
+abstract class Z {
+    init {
+        check(this)
+    }
+
+    abstract val b: B
+}
+
+class A(override val b: B) : Z()
+
+class B(val c: String)
+
+fun use(a: Any?) {}
+
+fun check(z: Z) {
+    use(z?.b?.c)
+}
+
+fun box(): String {
+    A(B(""))
+    return "OK"
+}
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java
index 7a437fa85b6..80331de86fe 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java
@@ -27348,6 +27348,18 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @Test
+        @TestMetadata("kt49136.kt")
+        public void testKt49136() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt");
+        }
+
+        @Test
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @Test
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java
index adb47408df1..e5fa8cddb4e 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java
@@ -27486,6 +27486,18 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @Test
+        @TestMetadata("kt49136.kt")
+        public void testKt49136() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt");
+        }
+
+        @Test
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @Test
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
diff --git a/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java b/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
index c48e76fc005..8711d4295ba 100644
--- a/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
+++ b/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
@@ -23199,6 +23199,16 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @TestMetadata("kt49136.kt")
+        public void testKt49136() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136.kt");
+        }
+
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
index b14ef72b7e7..73e1808d810 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
@@ -18138,6 +18138,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
index 638af2fe335..9d3344b0fba 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
@@ -17544,6 +17544,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
index 7b10c05e75f..0aa57e0ee29 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
@@ -17574,6 +17574,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java
index 6b38369bf6a..a23cf027bde 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java
@@ -14323,6 +14323,11 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt22410.kt");
         }
 
+        @TestMetadata("kt49136a.kt")
+        public void testKt49136a() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/kt49136a.kt");
+        }
+
         @TestMetadata("kt7774.kt")
         public void testKt7774() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");