diff --git a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/resolve/extensions/LLFirResolveExtensionTool.kt b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/resolve/extensions/LLFirResolveExtensionTool.kt
index bfdb3642596..2a4c3439e06 100644
--- a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/resolve/extensions/LLFirResolveExtensionTool.kt
+++ b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/resolve/extensions/LLFirResolveExtensionTool.kt
@@ -249,7 +249,14 @@ class LLFirResolveExtensionToolDeclarationProvider internal constructor(
             .mapNotNullTo(mutableListOf()) { it.kotlinFile.script }
     }
 
-    override fun computePackageNames(): Set<String>? = null
+    override fun computePackageNames(): Set<String>? =
+        buildSet {
+            extensionProvider.extensions.forEach { extension ->
+                extension.getContainedPackages().forEach { fqName ->
+                    add(fqName.asString())
+                }
+            }
+        }
 
     override val hasSpecificClassifierPackageNamesComputation: Boolean get() = false
     override val hasSpecificCallablePackageNamesComputation: Boolean get() = false