diff --git a/src/core/PlumedMain.cpp b/src/core/PlumedMain.cpp
index 742346c45ef88bffbd8d64466fc110806cd9ff9c..5c499bd8662272b1f14ded7c8e2432cdeb7ecb10 100644
--- a/src/core/PlumedMain.cpp
+++ b/src/core/PlumedMain.cpp
@@ -183,7 +183,7 @@ void PlumedMain::cmd(const std::string & word,void*val){
        atoms.setAtomsNlocal(*static_cast<int*>(val));
   } else if(word=="setAtomsGatindex"){
        CHECK_INIT(initialized,word);
-       CHECK_NULL(val,word);
+       //CHECK_NULL(val,word);
        atoms.setAtomsGatindex(static_cast<int*>(val));
   } else if(word=="setAtomsContiguous"){
        CHECK_INIT(initialized,word);