diff --git a/compiler/frontend/src/org/jetbrains/kotlin/analyzer/AbstractResolverForProject.kt b/compiler/frontend/src/org/jetbrains/kotlin/analyzer/AbstractResolverForProject.kt
index fddd38687ce..573cc1e9d56 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/analyzer/AbstractResolverForProject.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/analyzer/AbstractResolverForProject.kt
@@ -124,6 +124,7 @@ abstract class AbstractResolverForProject<M : ModuleInfo>(
      */
     private fun resolverForModuleDescriptorImpl(descriptor: ModuleDescriptor): ResolverForModule? {
         return projectContext.storageManager.compute {
+            descriptor.assertValid()
             val module = moduleInfoByDescriptor[descriptor]
             if (module == null) {
                 if (delegateResolver is EmptyResolverForProject<*>) {
diff --git a/core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ModuleDescriptorImpl.kt b/core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ModuleDescriptorImpl.kt
index 50b3775c4c9..b459556d04c 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ModuleDescriptorImpl.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ModuleDescriptorImpl.kt
@@ -153,6 +153,11 @@ class ModuleDescriptorImpl @JvmOverloads constructor(
 
     @Suppress("UNCHECKED_CAST")
     override fun <T> getCapability(capability: ModuleCapability<T>) = capabilities[capability] as? T
+
+    override fun toString(): String {
+        val toString = super.toString()
+        return if (isValid) toString else "$toString !isValid"
+    }
 }
 
 interface ModuleDependencies {