diff --git a/exec/load/tdfonts_lib.js b/exec/load/tdfonts_lib.js
index 8fc24aac47ff2d982760e1b1146cb494c0a302b0..d2c46f8f4668f8d6f0ae07f06b35c44a1e948668 100755
--- a/exec/load/tdfonts_lib.js
+++ b/exec/load/tdfonts_lib.js
@@ -397,6 +397,10 @@ function output(str, font) {
         padding = Math.floor(width - (linewidth + padding));
     }
 
+	linewidth += padding;
+	if(linewidth > width)
+		throw new Error(format("Rendered line width (%u) > screen width (%u)", linewidth, width));
+
     // Print each row of the font text
     for (var i = 0; i < maxheight; i++) {
         // Print padding spaces