diff --git a/davidson.h b/davidson.h
index b284f89..5b843a6 100644
--- a/davidson.h
+++ b/davidson.h
@@ -212,7 +212,7 @@ for(i=0; i<n; ++i)
 
 //orthogonalise to previous vectors
 typename LA_traits<T>::normtype vnorm= vec1.norm();
-if(vnorm) laerror("Zero Krylov vector in Davidson - perhaps try different initial guess");
+if(vnorm==0.) laerror("Zero Krylov vector in Davidson - perhaps try different initial guess");
 else
 {
 vec1 *= (1./vnorm);