diff --git a/src/FilterLists.Agent/Infrastructure/Web/UrlValidator.cs b/src/FilterLists.Agent/Infrastructure/Web/UrlValidator.cs
index 15af62157..99bdbf6e5 100644
--- a/src/FilterLists.Agent/Infrastructure/Web/UrlValidator.cs
+++ b/src/FilterLists.Agent/Infrastructure/Web/UrlValidator.cs
@@ -27,6 +27,14 @@ public UrlValidator(HttpClient httpClient, ILogger<UrlValidator> logger)
         public async Task<EntityUrl> ValidateAsync(EntityUrl entityUrl, CancellationToken cancellationToken)
         {
             var url = entityUrl.Url;
+            if (!Uri.IsWellFormedUriString(url.OriginalString, UriKind.Absolute))
+            {
+                entityUrl.SetBroken();
+                _logger.LogError(
+                    $"Url validation for ({url.OriginalString}) failed because it appears to be improperly formatted.");
+                return entityUrl;
+            }
+
             try
             {
                 using var response =