diff --git a/matlab/convert_particles_array_colmap.m b/matlab/convert_particles_array_colmap.m
index dc0fd3c..0c72c25 100644
--- a/matlab/convert_particles_array_colmap.m
+++ b/matlab/convert_particles_array_colmap.m
@@ -12,10 +12,12 @@ function [pp2] = convert_particles_array_colmap(pp1,col1,col2)
     nt = size(pp1,3);
     pp2 = zeros(ncol2,np,nt);
     
-    col2keys = col2.keys;
+    [colvals,idx] = sort(cell2mat(col2.values));
+    colkeys = col2.keys;
+    colkeys = {colkeys{idx}};
     for it=1:nt
       for icol=1:ncol2
-        key = col2keys{icol};
+        key = colkeys{icol};
         if col1.isKey(key)
           pp2(icol,:,it) = pp1(col1(key),:,it);
         end