diff --git a/tools/index-tools/src/org/jetbrains/index/stubs/SdkUtils.kt b/tools/index-tools/src/org/jetbrains/index/stubs/SdkUtils.kt
index 2a65e68c439b..e7452a6a7dec 100644
--- a/tools/index-tools/src/org/jetbrains/index/stubs/SdkUtils.kt
+++ b/tools/index-tools/src/org/jetbrains/index/stubs/SdkUtils.kt
@@ -48,7 +48,9 @@ fun openProjectWithSdk(projectPath: String,
 
     ModuleRootModificationUtil.setModuleSdk(module, sdk)
 
-    assert(ModuleRootManager.getInstance(module).orderEntries().classesRoots.isNotEmpty())
+    if (sdk != null) {
+      assert(ModuleRootManager.getInstance(module).orderEntries().classesRoots.isNotEmpty())
+    }
 
     assert(ModuleManager.getInstance(project).modules.size == 1)