diff --git a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/LowLevelFirApiFacade.kt b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/LowLevelFirApiFacade.kt
index 4529d6aa092..303d4035f63 100644
--- a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/LowLevelFirApiFacade.kt
+++ b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/LowLevelFirApiFacade.kt
@@ -77,6 +77,7 @@ object LowLevelFirApiFacade {
             body = builtFunction.body
             symbol = builtFunction.symbol as FirNamedFunctionSymbol
             resolvePhase = minOf(originalFunction.resolvePhase, FirResolvePhase.DECLARATIONS)
+            source = builtFunction.source
             this.session = state.firIdeSourcesSession
         }