diff --git a/commafeed-server/src/main/java/com/commafeed/backend/Urls.java b/commafeed-server/src/main/java/com/commafeed/backend/Urls.java
index 3ad98921..bdf36e1d 100644
--- a/commafeed-server/src/main/java/com/commafeed/backend/Urls.java
+++ b/commafeed-server/src/main/java/com/commafeed/backend/Urls.java
@@ -8,8 +8,10 @@ import org.netpreserve.urlcanon.Canonicalizer;
 import org.netpreserve.urlcanon.ParsedUrl;
 
 import lombok.experimental.UtilityClass;
+import lombok.extern.slf4j.Slf4j;
 
 @UtilityClass
+@Slf4j
 public class Urls {
 
 	private static final String ESCAPED_QUESTION_MARK = Pattern.quote("?");
@@ -42,7 +44,12 @@ public class Urls {
 			return null;
 		}
 
-		return URI.create(baseUrl).resolve(relativeUrl).toString();
+		try {
+			return URI.create(baseUrl).resolve(relativeUrl).toString();
+		} catch (IllegalArgumentException e) {
+			log.debug("Unable to create absolute url from relative url: {} base: {}", relativeUrl, baseUrl, e);
+			return null;
+		}
 	}
 
 	public static String removeTrailingSlash(String url) {
diff --git a/commafeed-server/src/test/java/com/commafeed/backend/UrlsTest.java b/commafeed-server/src/test/java/com/commafeed/backend/UrlsTest.java
index 04e26ba8..6b0cacfa 100644
--- a/commafeed-server/src/test/java/com/commafeed/backend/UrlsTest.java
+++ b/commafeed-server/src/test/java/com/commafeed/backend/UrlsTest.java
@@ -62,6 +62,10 @@ class UrlsTest {
 		Assertions.assertEquals("http://ergoemacs.org/emacs/elisp_all_about_lines.html",
 				Urls.toAbsolute("elisp_all_about_lines.html", "blog.xml", "http://ergoemacs.org/emacs/blog.xml"));
 
+		// invalid relative urls
+		Assertions.assertEquals("title:10001280",
+				Urls.toAbsolute("title:10001280", "https://www.berliner-zeitung.de", "https://www.berliner-zeitung.de/feed.xml"));
+
 	}
 
 	@Test