diff --git a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/AssignmentGenerator.kt b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/AssignmentGenerator.kt
index 6fc2d0abb77..db957b5410e 100644
--- a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/AssignmentGenerator.kt
+++ b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/AssignmentGenerator.kt
@@ -43,11 +43,15 @@ import org.jetbrains.kotlin.types.KotlinType
 
 class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGeneratorExtension(statementGenerator) {
 
-    fun generateAssignment(ktExpression: KtBinaryExpression): IrExpression {
-        val ktLeft = ktExpression.left!!
-        val irRhs = ktExpression.right!!.genExpr()
-        val irAssignmentReceiver = generateAssignmentReceiver(ktLeft, IrStatementOrigin.EQ)
-        return irAssignmentReceiver.assign(irRhs)
+    fun generateAssignment(ktExpression: KtBinaryExpression, origin: IrStatementOrigin): IrExpression {
+        return if (getResolvedCall(ktExpression) != null) {
+            generateAugmentedAssignment(ktExpression, origin)
+        } else {
+            val ktLeft = ktExpression.left!!
+            val irRhs = ktExpression.right!!.genExpr()
+            val irAssignmentReceiver = generateAssignmentReceiver(ktLeft, IrStatementOrigin.EQ)
+            irAssignmentReceiver.assign(irRhs)
+        }
     }
 
     fun generateAugmentedAssignment(ktExpression: KtBinaryExpression, origin: IrStatementOrigin): IrExpression {
@@ -55,7 +59,7 @@ class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGen
         val isSimpleAssignment = get(BindingContext.VARIABLE_REASSIGNMENT, ktExpression) ?: false
         val ktLeft = ktExpression.left!!
         val ktRight = ktExpression.right!!
-        val irAssignmentReceiver = generateAssignmentReceiver(ktLeft, origin)
+        val irAssignmentReceiver = generateAssignmentReceiver(ktLeft, origin, isAugmentedAssignment = true)
         val isDynamicCall = opResolvedCall.resultingDescriptor.isDynamic()
 
         return irAssignmentReceiver.assign { irLValue ->
@@ -167,7 +171,8 @@ class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGen
     private fun generateAssignmentReceiver(
         ktLeft: KtExpression,
         origin: IrStatementOrigin,
-        isAssignmentStatement: Boolean = true
+        isAssignmentStatement: Boolean = true,
+        isAugmentedAssignment: Boolean = false
     ): AssignmentReceiver {
         val ktExpr = KtPsiUtil.safeDeparenthesize(ktLeft)
         if (ktExpr is KtArrayAccessExpression) {
@@ -203,7 +208,14 @@ class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGen
                 else
                     createVariableValue(ktExpr, descriptor, origin)
             is PropertyDescriptor ->
-                generateAssignmentReceiverForProperty(descriptor, origin, ktExpr, resolvedCall, isAssignmentStatement)
+                generateAssignmentReceiverForProperty(
+                    descriptor,
+                    origin,
+                    ktExpr,
+                    resolvedCall,
+                    isAssignmentStatement,
+                    isAugmentedAssignment
+                )
             is FakeCallableDescriptorForObject ->
                 OnceExpressionValue(ktExpr.genExpr())
             is ValueDescriptor ->
@@ -263,7 +275,8 @@ class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGen
         origin: IrStatementOrigin,
         ktLeft: KtExpression,
         resolvedCall: ResolvedCall<*>,
-        isAssignmentStatement: Boolean
+        isAssignmentStatement: Boolean,
+        isAugmentedAssignment: Boolean
     ): AssignmentReceiver =
         when {
             descriptor.isDynamic() ->
@@ -280,8 +293,8 @@ class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGen
                         isAssignmentReceiver = isAssignmentStatement
                     )
                 )
-            origin == IrStatementOrigin.EQ && !descriptor.isVar -> {
-                // An assignment to a val property can only be its initialization in the constructor.
+            origin == IrStatementOrigin.EQ && !descriptor.isVar && !isAugmentedAssignment -> {
+                // An assignment to a val property can only be its initialization in the constructor or an augmented assignment.
                 val receiver = resolvedCall.dispatchReceiver ?: descriptor.dispatchReceiverParameter?.value
                 createBackingFieldLValue(ktLeft, descriptor, statementGenerator.generateReceiverOrNull(ktLeft, receiver), null)
             }
diff --git a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/OperatorExpressionGenerator.kt b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/OperatorExpressionGenerator.kt
index 668f195d963..1d535b64d0e 100644
--- a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/OperatorExpressionGenerator.kt
+++ b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/OperatorExpressionGenerator.kt
@@ -132,7 +132,7 @@ class OperatorExpressionGenerator(statementGenerator: StatementGenerator) : Stat
 
         return when (val irOperator = getInfixOperator(ktOperator)) {
             null -> throw AssertionError("Unexpected infix operator: $ktOperator")
-            IrStatementOrigin.EQ -> AssignmentGenerator(statementGenerator).generateAssignment(expression)
+            IrStatementOrigin.EQ -> AssignmentGenerator(statementGenerator).generateAssignment(expression, irOperator)
             in AUGMENTED_ASSIGNMENTS -> AssignmentGenerator(statementGenerator).generateAugmentedAssignment(expression, irOperator)
             IrStatementOrigin.ELVIS -> generateElvis(expression)
             in OPERATORS_DESUGARED_TO_CALLS -> generateBinaryOperatorAsCall(expression, irOperator)