diff --git a/compiler/testData/diagnostics/tests/inference/kt28598.kt b/compiler/testData/diagnostics/tests/inference/kt28598.kt
new file mode 100644
index 00000000000..ebf15016ee6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt28598.kt
@@ -0,0 +1,85 @@
+// !WITH_NEW_INFERENCE
+// !IDIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun case_1(a: MutableList<out MutableList<MutableList<MutableList<MutableList<MutableList<MutableList<Int?>?>?>?>?>?>?>?) {
+    if (a != null) {
+        val b = <!OI;DEBUG_INFO_SMARTCAST!>a<!>[0] // no SMARTCAST diagnostic
+        if (b != null) {
+            val c = <!DEBUG_INFO_SMARTCAST!>b<!>[0]
+            if (c != null) {
+                val d = <!DEBUG_INFO_SMARTCAST!>c<!>[0]
+                if (d != null) {
+                    val e = <!DEBUG_INFO_SMARTCAST!>d<!>[0]
+                    if (e != null) {
+                        val f = <!DEBUG_INFO_SMARTCAST!>e<!>[0]
+                        if (f != null) {
+                            val g = <!DEBUG_INFO_SMARTCAST!>f<!>[0]
+                            if (g != null) {
+                                val h = <!DEBUG_INFO_SMARTCAST!>g<!>[0]
+                                if (h != null) {
+                                    <!DEBUG_INFO_SMARTCAST!>h<!>.inc()
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+fun case_2(a: MutableList<out MutableList<MutableList<MutableList<out MutableList<MutableList<MutableList<out Int?>?>?>?>?>?>?>?) {
+    if (a != null) {
+        val b = <!OI;DEBUG_INFO_SMARTCAST!>a<!>[0] // no SMARTCAST diagnostic
+        if (b != null) {
+            val c = <!DEBUG_INFO_SMARTCAST!>b<!>[0]
+            if (c != null) {
+                val d = <!DEBUG_INFO_SMARTCAST!>c<!>[0]
+                if (d != null) {
+                    val e = <!OI;DEBUG_INFO_SMARTCAST!>d<!>[0] // no SMARTCAST diagnostic
+                    if (e != null) {
+                        val f = <!DEBUG_INFO_SMARTCAST!>e<!>[0]
+                        if (f != null) {
+                            val g = <!DEBUG_INFO_SMARTCAST!>f<!>[0]
+                            if (g != null) {
+                                val h = <!OI;DEBUG_INFO_SMARTCAST!>g<!>[0] // no SMARTCAST diagnostic
+                                if (h != null) {
+                                    <!DEBUG_INFO_SMARTCAST!>h<!>.inc()
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+fun case_3(a: MutableList<MutableList<MutableList<MutableList<MutableList<MutableList<MutableList<Int?>?>?>?>?>?>?>?) {
+    if (a != null) {
+        val b = <!DEBUG_INFO_SMARTCAST!>a<!>[0]
+        if (b != null) {
+            val c = <!DEBUG_INFO_SMARTCAST!>b<!>[0]
+            if (c != null) {
+                val d = <!DEBUG_INFO_SMARTCAST!>c<!>[0]
+                if (d != null) {
+                    val e = <!DEBUG_INFO_SMARTCAST!>d<!>[0]
+                    if (e != null) {
+                        val f = <!DEBUG_INFO_SMARTCAST!>e<!>[0]
+                        if (f != null) {
+                            val g = <!DEBUG_INFO_SMARTCAST!>f<!>[0]
+                            if (g != null) {
+                                val h = <!DEBUG_INFO_SMARTCAST!>g<!>[0]
+                                if (h != null) {
+                                    <!DEBUG_INFO_SMARTCAST!>h<!>.inc()
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt28598.txt b/compiler/testData/diagnostics/tests/inference/kt28598.txt
new file mode 100644
index 00000000000..faec0ef8ebf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt28598.txt
@@ -0,0 +1,5 @@
+package
+
+public fun case_1(/*0*/ a: kotlin.collections.MutableList<out kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.Int?>?>?>?>?>?>?): kotlin.Unit
+public fun case_2(/*0*/ a: kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.Int?>?>?>?>?>?>?): kotlin.Unit
+public fun case_3(/*0*/ a: kotlin.collections.MutableList<out kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.collections.MutableList<kotlin.Int?>?>?>?>?>?): kotlin.Unit
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index 7205d6b987d..bbc55994f25 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -9485,6 +9485,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 runTest("compiler/testData/diagnostics/tests/inference/kt1293.kt");
             }
 
+            @TestMetadata("kt28598.kt")
+            public void testKt28598() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/kt28598.kt");
+            }
+
             @TestMetadata("kt3184.kt")
             public void testKt3184() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/inference/kt3184.kt");
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
index 6559a239a09..6c2d82ef8f0 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
@@ -9485,6 +9485,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 runTest("compiler/testData/diagnostics/tests/inference/kt1293.kt");
             }
 
+            @TestMetadata("kt28598.kt")
+            public void testKt28598() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/kt28598.kt");
+            }
+
             @TestMetadata("kt3184.kt")
             public void testKt3184() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/inference/kt3184.kt");