diff --git a/matlab/read_grid_ucf.m b/matlab/read_grid_ucf.m
index 15f2232..421b256 100644
--- a/matlab/read_grid_ucf.m
+++ b/matlab/read_grid_ucf.m
@@ -17,7 +17,7 @@ function [xu,yu,zu,xv,yv,zv,xw,yw,zw,xp,yp,zp,...
     par = inputParser;
     addParamValue(par,'verbosity',0,@isnumeric);
     addParamValue(par,'debug',0,@isnumeric);
-    addParamValue(par,'tarmode',0,@isnumeric);
+    addParamValue(par,'tarmode',0,@isnumeric);  % deprecated
     parse(par,varargin{:});
 
     % Define sets to be read
@@ -26,11 +26,14 @@ function [xu,yu,zu,xv,yv,zv,xw,yw,zw,xp,yp,zp,...
     
     % Open UCF file and read
     obj = ucf('verbosity',par.Results.verbosity,'debug',par.Results.debug);
-    if par.Results.tarmode
+    switch class(file)
+    case 'char'
+      obj.open(file);
+    case {'ustar','ucfmulti'}
       ptr = file.pointer('grid.bin');
       obj.opentar(ptr);
-    else
-      obj.open(file);
+    otherwise
+      error('Input file type not supported: %s',class(file));
     end
   
     % Read raw data