diff --git a/src/analysis/Histogram.cpp b/src/analysis/Histogram.cpp
index fdd8f14525c4abfb6ddaa57aafc510e09e85ec6c..6d9271e62f3ec32db9bff44f3cceaf6f407f0295 100644
--- a/src/analysis/Histogram.cpp
+++ b/src/analysis/Histogram.cpp
@@ -224,6 +224,7 @@ void Histogram::performAnalysis(){
 
   Grid* gg; IFile oldf; oldf.link(*this); 
   if( usingMemory() && oldf.FileExist(gridfname) ){
+      if(fenergy) error("FREE-ENERGY only works with USE_ALL_DATA");
       oldf.open(gridfname);
       gg = Grid::create( "probs", getArguments(), oldf, gmin, gmax, gbin, false, false, false );
       oldf.close();