diff --git a/apps/contourclock/lib.js b/apps/contourclock/lib.js
index 41f778a9a..65a4622f4 100644
--- a/apps/contourclock/lib.js
+++ b/apps/contourclock/lib.js
@@ -1,49 +1,49 @@
 exports.drawClock = function(fontIndex) {
-	var digits = [];
-	if (!require("Storage").read("contourclock-"+Math.abs(parseInt(fontIndex+0.5))+".json")) return (false);
-  var font = JSON.parse(require("Storage").read("contourclock-"+Math.abs(parseInt(fontIndex+0.5))+".json"));
+  var digits = [];
+  fontFile=require("Storage").read("contourclock-"+Math.abs(parseInt(fontIndex+0.5))+".json");
+  if (fontFile==undefined) return(false); //exit if font file not found
+  var font = JSON.parse(fontFile);
   for (var n in font.characters) {
     digits.push({width: parseInt(font.characters[n].width),
-                height: font.size,
-                bpp: 2,
-                transparent: 1,
-                buffer:E.toArrayBuffer(atob(font.characters[n].buffer))});
+      height: font.size,
+      bpp: 2,
+      transparent: 1,
+      buffer:E.toArrayBuffer(atob(font.characters[n].buffer))});
+    }
+    if (n!=10) return (false); //font file seems to be invalid
+    var x=0;
+    var y = g.getHeight()/2-digits[0].height/2;
+    var date = new Date();
+    g.clearRect(0,38,g.getWidth()-1,138);
+    d1=parseInt(date.getHours()/10);
+    d2=parseInt(date.getHours()%10);
+    d3=10;
+    d4=parseInt(date.getMinutes()/10);
+    d5=parseInt(date.getMinutes()%10);
+    w1=digits[d1].width;
+    w2=digits[d2].width;
+    w3=digits[d3].width;
+    w4=digits[d4].width;
+    w5=digits[d5].width;
+    squeeze=(g.getWidth()-w5)/(w1+w2+w3+w4);
+    if (fontIndex<0) {
+      fg=g.theme.fg;
+      bg=g.theme.bg;
+      g.setColor(bg);
+      g.setBgColor(fg);
+    }
+    g.drawImage(digits[d1],x,y);
+    x+=parseInt(w1*squeeze);
+    g.drawImage(digits[d2],x,y);
+    x+=parseInt(w2*squeeze);
+    g.drawImage(digits[d3],x,y);
+    x+=parseInt(w3*squeeze);
+    g.drawImage(digits[d4],x,y);
+    x+=parseInt(w4*squeeze);
+    g.drawImage(digits[d5],x,y);
+    if (fontIndex<0) {
+      g.setColor(fg);
+      g.setBgColor(bg);
+    }
+    return font.name;
   }
-	var x=0;
-  var y = g.getHeight()/2-digits[0].height/2;
-  var date = new Date();
-	//g.clearRect(0,24,g.getWidth()-1,137);
-
-  g.clearRect(0,38,g.getWidth()-1,138);
-  d1=parseInt(date.getHours()/10);
-  d2=parseInt(date.getHours()%10);
-  d3=10;
-  d4=parseInt(date.getMinutes()/10);
-  d5=parseInt(date.getMinutes()%10);
-  w1=digits[d1].width;
-  w2=digits[d2].width;
-  w3=digits[d3].width;
-  w4=digits[d4].width;
-  w5=digits[d5].width;
-  squeeze=(g.getWidth()-w5)/(w1+w2+w3+w4);
-	if (fontIndex<0) {
-		fg=g.theme.fg;
-		bg=g.theme.bg;
-		g.setColor(bg);
-		g.setBgColor(fg);
-	}
-  g.drawImage(digits[d1],x,y);
-  x+=parseInt(w1*squeeze);
-  g.drawImage(digits[d2],x,y);
-  x+=parseInt(w2*squeeze);
-  g.drawImage(digits[d3],x,y);
-  x+=parseInt(w3*squeeze);
-  g.drawImage(digits[d4],x,y);
-  x+=parseInt(w4*squeeze);
-  g.drawImage(digits[d5],x,y);
-	if (fontIndex<0) {
-		g.setColor(fg);
-		g.setBgColor(bg);
-	}
-	return font.name;
-}