diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/PreliminaryLoopVisitor.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/PreliminaryLoopVisitor.kt
index da63de0ce91..9bdbd01cf08 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/PreliminaryLoopVisitor.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/PreliminaryLoopVisitor.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.resolve.dfa
 
+import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.fir.FirElement
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.expressions.*
@@ -41,6 +42,8 @@ class PreliminaryLoopVisitor {
         }
 
         override fun visitVariableAssignment(variableAssignment: FirVariableAssignment, data: FirStatement?) {
+            if (variableAssignment.source?.kind == KtFakeSourceElementKind.DesugaredIncrementOrDecrement) return
+
             val reference = variableAssignment.lValue as? FirNamedReference
             if (reference != null) {
                 requireNotNull(data)
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt
index 4c61f334a5c..8127910c036 100644
--- a/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt
@@ -2,7 +2,7 @@ public fun foo() {
     var i: Any = 1
     if (i is Int) {
         while (i != 10) {
-            i<!UNRESOLVED_REFERENCE!>++<!>
+            i++
         }
     }
 }
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt
index 30698d4327c..bf54f66b125 100644
--- a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt
@@ -2,7 +2,7 @@ public fun foo() {
     var i: Int? = 1
     if (i != null) {
         while (i != 10) {
-            i<!UNSAFE_CALL!>++<!>
+            i++
         }
     }
 }