diff --git a/src/adjmat/AdjacencyMatrixBase.cpp b/src/adjmat/AdjacencyMatrixBase.cpp
index f07d5bb0cc8d0dc999fc4f51d1ba910cbf2317b9..82cb7d4d7ba9027dd1b826f41c9c76c55ce46993 100644
--- a/src/adjmat/AdjacencyMatrixBase.cpp
+++ b/src/adjmat/AdjacencyMatrixBase.cpp
@@ -32,6 +32,7 @@ namespace adjmat {
 void AdjacencyMatrixBase::registerKeywords( Keywords& keys ){
   multicolvar::MultiColvarBase::registerKeywords( keys );
   keys.add("compulsory","WTOL","0.0","if the base multicolvars have weights then you must define a hard cutoff on those you want to consider explicitally");
+  keys.remove("LOWMEM"); keys.use("HIGHMEM");
 }
 
 AdjacencyMatrixBase::AdjacencyMatrixBase(const ActionOptions& ao):