diff --git a/gmlmip_stub.cc b/gmlmip_stub.cc
index 8548e27aa3569b7c5d5fa9b5bd978bc025e1c624..bf83b1846a2283c249bc12ce94718f297576f8a4 100644
--- a/gmlmip_stub.cc
+++ b/gmlmip_stub.cc
@@ -75,6 +75,7 @@ CAMLprim value gmlRules_stub(value modalities) {
             Bool_val(vpos),
             Int_val(vcnt)),
             Int_val(vformula)));
+        block = Field(block, 1);
     }
     // Do one rule step and save result in rulevec
     GMLConclusion rulevec = gmlmip_onestep_gml(modvec);