diff --git a/rtengine/FTblockDN.cc b/rtengine/FTblockDN.cc
index 20f5b5e1b..288c9c994 100644
--- a/rtengine/FTblockDN.cc
+++ b/rtengine/FTblockDN.cc
@@ -2185,7 +2185,7 @@ float ImProcFunctions::MadRgb(float * DataList, const int datalen)
     int i;
 
     for (i = 0; i < datalen; ++i) {
-        histo[min(65536, abs(static_cast<int>(DataList[i])))]++;
+        histo[min(65535, abs(static_cast<int>(DataList[i])))]++;
     }
 
     //find median of histogram