diff --git a/MVMCoreUI/Behaviors/ReplaceableMoleculeBehaviorModel.swift b/MVMCoreUI/Behaviors/ReplaceableMoleculeBehaviorModel.swift
index c35a5d19..3d234065 100644
--- a/MVMCoreUI/Behaviors/ReplaceableMoleculeBehaviorModel.swift
+++ b/MVMCoreUI/Behaviors/ReplaceableMoleculeBehaviorModel.swift
@@ -49,9 +49,15 @@ public class ReplaceableMoleculeBehavior: PageMoleculeTransformationBehavior, Pa
     public func onPageNew(rootMolecules: [MoleculeModelProtocol], _ delegateObject: MVMCoreUIDelegateObject?, changes: inout [MoleculeModelProtocol]) -> [MoleculeModelProtocol]? {
         self.delegateObject = delegateObject
         
-        let moleculeModels = moleculeIds.compactMap { moleculeId in
+        let moleculeModels: [MoleculeModelProtocol] = moleculeIds.compactMap { moleculeId in
             do {
-                return try delegateObject?.moleculeDelegate?.getModuleWithName(moleculeId)
+                guard let molecule = try delegateObject?.moleculeDelegate?.getModuleWithName(moleculeId) else {
+                    return nil // Valid. Module might not be present yet.
+                }
+                guard molecule.id == moleculeId else {
+                    throw MolecularError.validationError("The module name \(moleculeId) must match the molecule id \(molecule.id) it encloses!")
+                }
+                return molecule
             } catch {
                 let coreError = MVMCoreErrorObject.createErrorObject(for: error, location: String(describing: type(of: self)))!
                 if let error = error as? HumanReadableDecodingErrorProtocol {