diff --git a/code/nel/src/3d/instance_lighter.cpp b/code/nel/src/3d/instance_lighter.cpp
index f754ebb8b..d21f80e4e 100644
--- a/code/nel/src/3d/instance_lighter.cpp
+++ b/code/nel/src/3d/instance_lighter.cpp
@@ -408,6 +408,12 @@ void CInstanceLighter::light (const CInstanceGroup &igIn, CInstanceGroup &igOut,
 		string name= _Instances[i].Name;
 		bool	shapeFound= true;
 
+		if (toLower (CFile::getExtension (name)) == "pacs_prim")
+		{
+			nlwarning("EXPORT BUG: Can't read %s (not a shape), should not be part of .ig!", name.c_str());
+			continue;
+		}
+
 		// Try to find the shape in the UseShapeMap.
 		std::map<string, IShape*>::const_iterator iteMap= lightDesc.UserShapeMap.find (name);