diff --git a/src/main/java/org/olat/modules/cp/NekoHtmlPageHandler.java b/src/main/java/org/olat/modules/cp/NekoHtmlPageHandler.java
index 63c22bddc427c1af51b1ad5a8a62fa390108c65b..75e7617f26491712f4a1b44402023667fbaf6d64 100644
--- a/src/main/java/org/olat/modules/cp/NekoHtmlPageHandler.java
+++ b/src/main/java/org/olat/modules/cp/NekoHtmlPageHandler.java
@@ -166,10 +166,14 @@ public class NekoHtmlPageHandler extends DefaultHandler {
 			
 			String tmpUri = uri;
 			VFSContainer tmpDir = startDir;
-			while(tmpUri.startsWith("../")) {
+			while(tmpUri.startsWith("../") && tmpDir != null) {
 				tmpDir = tmpDir.getParentContainer();
 				tmpUri = tmpUri.substring(3);
 			}
+			if (tmpDir == null) {
+				// no local file uri, return unchanged
+				return uri;
+			}
 			
 			String diffPath = getRelativeResultingPath(tmpDir);
 			if(StringHelper.containsNonWhitespace(diffPath)) {