diff --git a/analysis/analysis-api-standalone/src/org/jetbrains/kotlin/analysis/api/standalone/StandaloneAnalysisAPISessionBuilder.kt b/analysis/analysis-api-standalone/src/org/jetbrains/kotlin/analysis/api/standalone/StandaloneAnalysisAPISessionBuilder.kt
index 8fb51299dbbfc..b849405a12918 100644
--- a/analysis/analysis-api-standalone/src/org/jetbrains/kotlin/analysis/api/standalone/StandaloneAnalysisAPISessionBuilder.kt
+++ b/analysis/analysis-api-standalone/src/org/jetbrains/kotlin/analysis/api/standalone/StandaloneAnalysisAPISessionBuilder.kt
@@ -96,6 +96,9 @@ public class StandaloneAnalysisAPISessionBuilder(
     private lateinit var projectStructureProvider: KotlinStaticProjectStructureProvider
 
     public fun buildKtModuleProvider(init: KtModuleProviderBuilder.() -> Unit) {
+        contract {
+            callsInPlace(init, InvocationKind.EXACTLY_ONCE)
+        }
         projectStructureProvider = buildProjectStructureProvider(kotlinCoreProjectEnvironment.environment, project, init)
     }