diff --git a/js_src/previewRendering.js b/js_src/previewRendering.js
index c28314b..30ce9dd 100644
--- a/js_src/previewRendering.js
+++ b/js_src/previewRendering.js
@@ -83,7 +83,10 @@ var debug_redrawSimplification = 6;
 function redrawPreview(redrawLess) {
   if (redrawLess == undefined) redrawLess = false;
 
-  if (_points.length < 2) return;
+  if (_points.length < 2) {
+	  previewCtx.clearRect(0, 0, preview.width, preview.height);
+	  return;
+  }
 
   if (!redrawLess) {
     //debug_redrawSimplification = Math.round(_points.length / 65);
@@ -345,4 +348,4 @@ function updatePreview(_x, _y, redrawLess) {
   updatePrevY = _y;
 
 }
-//*/
\ No newline at end of file
+//*/
diff --git a/js_src/sketches.js b/js_src/sketches.js
index aecc9c5..a376ff3 100644
--- a/js_src/sketches.js
+++ b/js_src/sketches.js
@@ -54,7 +54,7 @@ function setCurrentSketchId(sId) {
 }
 
 function updatePrevNextButtonStateOnClear() {
-	enableButton(btnPrevious, prevDoodle);
+	if (numSavedSketches > 0) enableButton(btnPrevious, prevDoodle);
 	disableButton(btnNext);
 	currentSketchId = numSavedSketches+1; //after the end of the list
 	disableButton(btnSave);