diff --git a/inst/htmlwidgets/lib/datatables-extensions/Buttons/js/buttons.html5.min.js b/inst/htmlwidgets/lib/datatables-extensions/Buttons/js/buttons.html5.min.js
index 222bb320..908d85d3 100644
--- a/inst/htmlwidgets/lib/datatables-extensions/Buttons/js/buttons.html5.min.js
+++ b/inst/htmlwidgets/lib/datatables-extensions/Buttons/js/buttons.html5.min.js
@@ -436,10 +436,129 @@
             p.title && (r([p.title], g), k(g, d.header.length - 1));
             p.messageTop && (r([p.messageTop],
                 g), k(g, d.header.length - 1));
-            c.header && (r(d.header, g), i("row:last c", e).attr("s", "2"));
+            /* BEGIN ADD */
+            //c.header && (r(d.header, g), i("row:last c", e).attr("s", "2"));
+            var mgCnt = 0;
+            var merges=[];
+			if (c.header) {
+                //for each header row
+                for(i=0; i < d.header.length; i++)
+                {
+                  //for each column (cell) in the row
+                  for(j=0; j<d.header[i].length; j++)
+                  {
+                    //look for a non-colspan/rowspan cell
+                    if(d.header[i][j] != "" && d.header[i][j] != "")
+                    {
+                      var startRow = i;
+                      var startCol = j;
+                      var endRow = i;
+                      var endCol = j;
+                      
+                      //console.log(i+":"+j+"="+b.header[i][j]);
+                      
+                      //lookahead
+                      if(j+1 < d.header[i].length)
+                      if(d.header[i][j+1] == "") //is the cell to the right a colspan?
+                      { 
+                        //console.log("cspan start:"+b.header[i][j]);
+                        startCol = j;
+                        endCol = j+1;
+
+                        //get to the last column in the colspan
+                        while(endCol < d.header[i].length &&d.header[i][endCol] == "")
+                        {
+                          //b.header[i][endCol] = ""; //Use if cspan is a special char/sequence
+                          endCol++;
+                        }
+                        endCol--;
+                      }
+                      
+                      if(i+1 < d.header.length)
+                      if(d.header[i+1][j] == "") //is the cell below a rowspan?
+                      {  
+                        //console.log("rspan start:"+b.header[i][j]);
+                        startRow = i;
+                        endRow = i+1;
+
+                        //get to the last row in the rowspan
+                        while(endRow < d.header.length && d.header[endRow][j] == "")
+                        {
+                          //b.header[endRow][j] = ""; //Use if rowspan is a special char/sequence
+                          endRow++;
+                        }
+                      }
+                      
+                      //create and store merge ranges
+                      //if endCol or endRow show movement
+                      if(startRow != endRow || startCol != endCol)
+                      {
+                        sC = colLetter(startCol); //convert startCol to excel column letter
+                        sR = startRow+1;
+                        eC = colLetter(endCol); //conver endCol to excel column letter
+                        eR = endRow;
+                        
+                        //console.log("sC="+sC);
+                        merges[mgCnt] = sC+""+sR; //start of range
+                        
+                        //console.log("endrow > startrow="+endRow+">"+startRow);
+                        //console.log("endCol > startcol="+endCol+">"+startCol);
+
+                        if(endCol > startCol) //end column
+                          merges[mgCnt] = merges[mgCnt] + ":" + eC;
+                        else
+                          merges[mgCnt] = merges[mgCnt] + ":" + sC;
+                        
+                        if(endRow > startRow) //end row
+                          merges[mgCnt] = merges[mgCnt] + eR;
+                        else
+                          merges[mgCnt] = merges[mgCnt] + sR;
+                          
+                        //console.log("merges[mgCnt]="+merges[mgCnt]);
+                        
+                        mgCnt++; //increment number of merge ranges
+                      }
+                    }
+                  }
+                }
+                
+                //add multiple headers
+                for (i = 0; i < b.header.length; i++){
+                  d(b.header[i], e);
+                  g("row c", f).attr("s", "2"); //maybe should be outside the loop?
+                }
+            }
+            /* END ADD */
             for (var o = 0, u = d.body.length; o < u; o++) r(d.body[o], g);
             c.footer && d.footer && (r(d.footer, g), i("row:last c", e).attr("s", "2"));
             p.messageBottom && (r([p.messageBottom], g), k(g, d.header.length - 1));
+            
+            /* BEGIN ADD */
+			//if we have merges
+            if (mgCnt > 0)
+            {
+              //create a mergeCells section
+              z = o(f, "mergeCells", {
+                  attr: {
+                      count: mgCnt,
+                  }
+              });
+              
+              //add each merge range as a child
+              for(i=0;i<mgCnt;i++)
+              {
+                n = o(f, "mergeCell", {
+                        attr: {
+                          ref: merges[i]
+                        }
+                      });
+                z.appendChild(n);
+              }
+            }
+            if(z.children)
+              g("worksheet", f).append(z) //add to the worksheet
+
+            /*END ADD */
             r = q(e, "cols");
             i("worksheet", e).prepend(r);
             k = 0;