diff --git a/compiler/fir/fir-deserialization/src/org/jetbrains/kotlin/fir/deserialization/ClassDeserialization.kt b/compiler/fir/fir-deserialization/src/org/jetbrains/kotlin/fir/deserialization/ClassDeserialization.kt
index da46bd7f3a5..38bbaa68b48 100644
--- a/compiler/fir/fir-deserialization/src/org/jetbrains/kotlin/fir/deserialization/ClassDeserialization.kt
+++ b/compiler/fir/fir-deserialization/src/org/jetbrains/kotlin/fir/deserialization/ClassDeserialization.kt
@@ -69,6 +69,7 @@ fun deserializeClassToSymbol(
         isData = Flags.IS_DATA.get(classProto.flags)
         isInline = Flags.IS_INLINE_CLASS.get(classProto.flags)
         isExternal = Flags.IS_EXTERNAL_CLASS.get(classProto.flags)
+        isFun = Flags.IS_FUN_INTERFACE.get(classProto.flags)
     }
     val isSealed = modality == Modality.SEALED
     val annotationDeserializer = defaultAnnotationDeserializer ?: FirBuiltinAnnotationDeserializer(session)
diff --git a/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt b/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt
index 70f94c83c2c..06c13da3428 100644
--- a/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt
+++ b/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt
@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 // FILE: A.kt