diff --git a/src/cairo-ft-font.c b/src/cairo-ft-font.c
index 59a5acb..8851387 100644
--- a/cairo/src/cairo-ft-font.c
+++ b/cairo/src/cairo-ft-font.c
@@ -62,6 +62,10 @@
  */
 #define MAX_OPEN_FACES 10
 
+/* This is the maximum font size we allow to be passed to FT_Set_Char_Size
+ */
+#define MAX_FONT_SIZE 1000
+
 /*
  * The simple 2x2 matrix is converted into separate scale and shape
  * factors so that hinting works right
@@ -643,9 +647,18 @@ _cairo_ft_unscaled_font_set_scale (cairo
     FT_Set_Transform(unscaled->face, &mat, NULL);
 
     if ((unscaled->face->face_flags & FT_FACE_FLAG_SCALABLE) != 0) {
+        double x_scale = sf.x_scale;
+        double y_scale = sf.y_scale;
+        if (x_scale > MAX_FONT_SIZE) {
+            x_scale = MAX_FONT_SIZE;
+        }
+        if (y_scale > MAX_FONT_SIZE) {
+            y_scale = MAX_FONT_SIZE;
+        }
+
 	error = FT_Set_Char_Size (unscaled->face,
-				  sf.x_scale * 64.0,
-				  sf.y_scale * 64.0,
+				  x_scale * 64.0,
+				  y_scale * 64.0,
 				  0, 0);
 	assert (error == 0);
     } else {