diff --git a/src/ftgrid.c b/src/ftgrid.c
index 119e838e8cbe2cd86ed6152212482489f2fb3944..d7462344317a336244e08ed36aa4c714bee567ee 100644
--- a/src/ftgrid.c
+++ b/src/ftgrid.c
@@ -1291,9 +1291,9 @@
     if ( !err )
     {
       int  xmin = 0;
-      int  ymin = size->metrics.descender;
-      int  xmax = size->metrics.max_advance;
-      int  ymax = size->metrics.ascender;
+      int  ymin = size->metrics.y_ppem * -14;
+      int  xmax = size->metrics.x_ppem * 64;
+      int  ymax = size->metrics.y_ppem * 60;
 
       float  x_scale, y_scale;