diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.kt
new file mode 100644
index 00000000000..44190e099e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.kt
@@ -0,0 +1,11 @@
+fun <K, V> MutableMap<K, V>.set(k: K, v: V) {}
+
+fun foo(a: MutableMap<String, String>, x: String?) {
+    a[x!!] = <!DEBUG_INFO_SMARTCAST!>x<!>
+    a[<!DEBUG_INFO_SMARTCAST!>x<!>] = x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>
+}
+
+fun foo1(a: MutableMap<String, String>, x: String?) {
+    <!TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS!>a[x]<!> = x!!
+    a[x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>] = <!DEBUG_INFO_SMARTCAST!>x<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.txt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.txt
new file mode 100644
index 00000000000..d73971438fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.txt
@@ -0,0 +1,5 @@
+package
+
+internal fun foo(/*0*/ a: kotlin.MutableMap<kotlin.String, kotlin.String>, /*1*/ x: kotlin.String?): kotlin.Unit
+internal fun foo1(/*0*/ a: kotlin.MutableMap<kotlin.String, kotlin.String>, /*1*/ x: kotlin.String?): kotlin.Unit
+internal fun </*0*/ K, /*1*/ V> kotlin.MutableMap<K, V>.set(/*0*/ k: K, /*1*/ v: V): kotlin.Unit
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java
index 45766b98a54..2fcc46f0e40 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java
@@ -11323,6 +11323,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/smartCasts/varnotnull"), Pattern.compile("^(.+)\\.kt$"), true);
                 }
 
+                @TestMetadata("kt2865.kt")
+                public void testKt2865() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt2865.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("kt3224.kt")
                 public void testKt3224() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt3224.kt");