diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirSupertypeResolverTransformer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirSupertypeResolverTransformer.kt
index 91e4f09a7cb..d9f7197305a 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirSupertypeResolverTransformer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirSupertypeResolverTransformer.kt
@@ -30,7 +30,7 @@ class FirSupertypeResolverTransformer : FirAbstractTreeTransformer() {
     private lateinit var file: FirFile
 
     override fun transformFile(file: FirFile, data: Nothing?): CompositeTransformResult<FirFile> {
-        firSession = file.session
+        firSession = file.fileSession
         this.file = file
         return super.transformFile(file, data)
     }