diff --git a/src/main/java/org/olat/core/gui/render/velocity/VelocityRenderDecorator.java b/src/main/java/org/olat/core/gui/render/velocity/VelocityRenderDecorator.java
index 9522642183c56fe94234543057fc3a6856aa5892..2353da27a64864a86dfa1e75b1c668a935e611bf 100644
--- a/src/main/java/org/olat/core/gui/render/velocity/VelocityRenderDecorator.java
+++ b/src/main/java/org/olat/core/gui/render/velocity/VelocityRenderDecorator.java
@@ -710,6 +710,17 @@ public class VelocityRenderDecorator implements Closeable {
 		return notEmpty;
 	}
 	
+	public int parseInt(String text) {
+		try {
+			if(StringHelper.containsNonWhitespace(text)) {
+				return Integer.parseInt(text);
+			}
+			return -1;
+		} catch (NumberFormatException e) {
+			return -1;
+		}
+	}
+	
 	/**
 	 * @param componentName
 	 * @return true if the component with name componentName is a child of the current container. Used to "if" the render 
diff --git a/src/main/java/org/olat/ims/qti21/ui/components/_content/drawingInteraction.html b/src/main/java/org/olat/ims/qti21/ui/components/_content/drawingInteraction.html
index e4100668ebdb34d596a244fb2569007588fbe09e..e54e00e355853b8cbc5a4da3f0b42bd35c4456bf 100644
--- a/src/main/java/org/olat/ims/qti21/ui/components/_content/drawingInteraction.html
+++ b/src/main/java/org/olat/ims/qti21/ui/components/_content/drawingInteraction.html
@@ -47,9 +47,8 @@
 	</div>
 	#end
 	
-	#set($Integer = 0)
-	#set($widthWithBorder = $Integer.parseInt(${interaction.object.width}) + 2)
-	#set($heightWithBorder = $Integer.parseInt(${interaction.object.height}) + 2)
+	#set($widthWithBorder = $r.parseInt(${interaction.object.width}) + 2)
+	#set($heightWithBorder = $r.parseInt(${interaction.object.height}) + 2)
 	<div id="sketch" style="border:1px solid black; width:${widthWithBorder}px; height:${heightWithBorder}px;" draggable="false" ondragstart="return false;">
 		<canvas id="paint" width="${interaction.object.width}" height="${interaction.object.height}" style="background:url('${r.convertLinkFull($interaction.object.data)}')" draggable="false" ondragstart="return false;"></canvas>
 	</div>