diff --git a/idea/idea-analysis/src/org/jetbrains/jet/plugin/configuration/ModuleTypeCache.kt b/idea/idea-analysis/src/org/jetbrains/jet/plugin/configuration/ModuleTypeCache.kt
index 40e3ab3a618..8dcc5df9947 100644
--- a/idea/idea-analysis/src/org/jetbrains/jet/plugin/configuration/ModuleTypeCache.kt
+++ b/idea/idea-analysis/src/org/jetbrains/jet/plugin/configuration/ModuleTypeCache.kt
@@ -47,7 +47,7 @@ class ModuleTypeCacheManager private (project: Project) {
     fun isGradleModule(module: Module) = getModuleType(module) == ModuleType.GRADLE
 
     private fun getModuleType(module: Module): ModuleType? {
-        return cachedValue?.getValue(module)
+        return cachedValue.getValue(module)
     }
 
     private class VfsModificationTracker(project: Project): SimpleModificationTracker() {
diff --git a/idea/idea-analysis/src/org/jetbrains/jet/plugin/stubindex/JetSourceFilterScope.java b/idea/idea-analysis/src/org/jetbrains/jet/plugin/stubindex/JetSourceFilterScope.java
index e4bb1aaa22c..bbc8cea70be 100644
--- a/idea/idea-analysis/src/org/jetbrains/jet/plugin/stubindex/JetSourceFilterScope.java
+++ b/idea/idea-analysis/src/org/jetbrains/jet/plugin/stubindex/JetSourceFilterScope.java
@@ -59,12 +59,22 @@ public class JetSourceFilterScope extends DelegatingGlobalSearchScope {
             return false;
         }
 
-        if (index.isInSourceContent(file)) {
+        return isInProjectSources(project, file, index, /* withClassesRoots */ true, includeLibraries);
+    }
+
+    public static boolean isInProjectSources(
+            @NotNull Project project,
+            @NotNull VirtualFile file,
+            @NotNull ProjectFileIndex fileIndex,
+            boolean withClassesRoots,
+            boolean withLibraries
+    ) {
+        if (fileIndex.isInSourceContent(file)) {
             return !JetModuleTypeManager.getInstance().isKtFileInGradleProjectInWrongFolder(file, project);
         }
 
-        if (!includeLibraries) return false;
+        if (!withLibraries) return false;
 
-        return index.isInLibraryClasses(file) || index.isInLibrarySource(file);
+        return (withClassesRoots && fileIndex.isInLibraryClasses(file)) || fileIndex.isInLibrarySource(file);
     }
 }
diff --git a/idea/idea-analysis/src/org/jetbrains/jet/plugin/util/ProjectRootsUtil.kt b/idea/idea-analysis/src/org/jetbrains/jet/plugin/util/ProjectRootsUtil.kt
index 324d1a1d2ac..56f2e4d64bb 100644
--- a/idea/idea-analysis/src/org/jetbrains/jet/plugin/util/ProjectRootsUtil.kt
+++ b/idea/idea-analysis/src/org/jetbrains/jet/plugin/util/ProjectRootsUtil.kt
@@ -16,15 +16,11 @@
 
 package org.jetbrains.jet.plugin.util
 
-import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.roots.ProjectFileIndex
-import com.intellij.openapi.util.Computable
-import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.psi.PsiElement
-import com.intellij.psi.PsiFile
-import org.jetbrains.jet.plugin.configuration.JetModuleTypeManager
 import kotlin.platform.platformStatic
 import org.jetbrains.jet.plugin.util.application.runReadAction
+import org.jetbrains.jet.plugin.stubindex.JetSourceFilterScope
 
 public object ProjectRootsUtil {
     platformStatic
@@ -36,15 +32,9 @@ public object ProjectRootsUtil {
             val virtualFile = containingFile.getVirtualFile()
             if (virtualFile == null) return@runReadAction false
 
-            val index = ProjectFileIndex.SERVICE.getInstance(element.getProject())
-            val isInSourceRoot = if (includeLibrarySources)
-                index.isInSource(virtualFile)
-            else
-                index.isInSourceContent(virtualFile)
-
-            if (!isInSourceRoot) return@runReadAction false
-
-            return@runReadAction !JetModuleTypeManager.getInstance()!!.isKtFileInGradleProjectInWrongFolder(element)
+            val project = element.getProject()
+            val index = ProjectFileIndex.SERVICE.getInstance(project)
+            return@runReadAction JetSourceFilterScope.isInProjectSources(project, virtualFile, index, false, includeLibrarySources)
         }!!
     }