diff --git a/src/main/java/org/olat/core/servlets/HeadersFilter.java b/src/main/java/org/olat/core/servlets/HeadersFilter.java
index 3facbe90793e97ef98417a740f687c816c4e6605..e916e77026bf8b37335eeb1e6349ff0b0cb05ef6 100644
--- a/src/main/java/org/olat/core/servlets/HeadersFilter.java
+++ b/src/main/java/org/olat/core/servlets/HeadersFilter.java
@@ -214,9 +214,10 @@ public class HeadersFilter implements Filter {
 	}
 	
 	private void appendMathJaxUrl(StringBuilder sb) {
-		if(StringHelper.containsNonWhitespace(WebappHelper.getMathJaxCdn())) {
+		String mathJaxCdn = WebappHelper.getMathJaxCdn();
+		if(StringHelper.containsNonWhitespace(mathJaxCdn)
+				&& (mathJaxCdn.startsWith("//") || mathJaxCdn.startsWith("https://") || mathJaxCdn.startsWith("http://"))) {
 			try {
-				String mathJaxCdn = WebappHelper.getMathJaxCdn();
 				if(mathJaxCdn.startsWith("//")) {
 					mathJaxCdn = "https:" + mathJaxCdn;
 				}