diff --git a/core/src/main/java/info/openrocket/core/file/openrocket/importt/SingleSimulationHandler.java b/core/src/main/java/info/openrocket/core/file/openrocket/importt/SingleSimulationHandler.java
index 829425a06..ab192e57e 100644
--- a/core/src/main/java/info/openrocket/core/file/openrocket/importt/SingleSimulationHandler.java
+++ b/core/src/main/java/info/openrocket/core/file/openrocket/importt/SingleSimulationHandler.java
@@ -87,6 +87,7 @@ class SingleSimulationHandler extends AbstractElementHandler {
 			extensions.add(compatibilityExtension(content.trim()));
 		} else if (element.equals("extension") && !StringUtils.isEmpty(attributes.get("extensionid"))) {
 			String id = attributes.get("extensionid");
+			id = id.replace("net.sf.openrocket", "info.openrocket.core");
 			SimulationExtension extension = null;
 			Set<SimulationExtensionProvider> extensionProviders = Application.getInjector()
 					.getInstance(new Key<Set<SimulationExtensionProvider>>() {