diff --git a/core/src/net/sf/openrocket/simulation/extension/impl/ScriptingExtension.java b/core/src/net/sf/openrocket/simulation/extension/impl/ScriptingExtension.java
index d3d3380b3..3569d2aae 100644
--- a/core/src/net/sf/openrocket/simulation/extension/impl/ScriptingExtension.java
+++ b/core/src/net/sf/openrocket/simulation/extension/impl/ScriptingExtension.java
@@ -103,7 +103,9 @@ public class ScriptingExtension extends AbstractSimulationExtension {
 			throw new SimulationException("Invalid script: " + e.getMessage());
 		}
 		
-		// TODO: Check for implementation first
+		if (!(engine instanceof Invocable)) {
+			throw new SimulationException("The scripting language '" + getLanguage() + "' does not implement the Invocable interface");
+		}
 		return new ScriptingSimulationListener((Invocable) engine);
 	}