diff --git a/src/SeoToolkit.Umbraco.Sitemap.Core/Common/SitemapGenerators/SitemapGenerator.cs b/src/SeoToolkit.Umbraco.Sitemap.Core/Common/SitemapGenerators/SitemapGenerator.cs
index a813bb08..3e189216 100644
--- a/src/SeoToolkit.Umbraco.Sitemap.Core/Common/SitemapGenerators/SitemapGenerator.cs
+++ b/src/SeoToolkit.Umbraco.Sitemap.Core/Common/SitemapGenerators/SitemapGenerator.cs
@@ -178,7 +178,7 @@ private IEnumerable<XElement> ToXmlElements(IEnumerable<SitemapNodeItem> nodes)
                 var selfItem = new XElement(_namespace + "url");
                 selfItem.Add(new XElement(_namespace + "loc", node.Url));
                 if (node.LastModifiedDate != null)
-                    selfItem.Add(new XElement(_namespace + "lastmod", node.LastModifiedDate.Value.ToString("yyyy-MM-dd")));
+                    selfItem.Add(new XElement(_namespace + "lastmod", node.LastModifiedDate.Value.ToString(_settings.LastModifiedFormat)));
                 if (!string.IsNullOrWhiteSpace(node.ChangeFrequency))
                     selfItem.Add(new XElement(_namespace + "changefreq", node.ChangeFrequency));
                 if (node.Priority != null)
diff --git a/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapAppSettingsModel.cs b/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapAppSettingsModel.cs
index 5507fff7..ad3e378b 100644
--- a/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapAppSettingsModel.cs
+++ b/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapAppSettingsModel.cs
@@ -12,6 +12,7 @@ public class SitemapAppSettingsModel
         public string PriorityFieldAlias { get; set; } = "priority";
 
         public string ReturnContentType { get; set; } = "application/xml";
+        public string LastModifiedFormat { get; set; } = "yyyy-MM-ddTHH:mm:sszzz";
         public string[] DisabledModules { get; set; } = Array.Empty<string>();
     }
 }
diff --git a/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapConfig.cs b/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapConfig.cs
index eb756723..f77882f1 100644
--- a/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapConfig.cs
+++ b/src/SeoToolkit.Umbraco.Sitemap.Core/Config/Models/SitemapConfig.cs
@@ -12,6 +12,7 @@ public class SitemapConfig
         public string PriorityFieldAlias { get; set; } = "priority";
 
         public string ReturnContentType { get; set; } = "application/xml";
+        public string LastModifiedFormat { get; set; } = "yyyy-MM-ddTHH:mm:sszzz";
         public string[] DisabledModules { get; set; } = Array.Empty<string>();
     }
 }
diff --git a/src/SeoToolkit.Umbraco.Sitemap.Core/Config/SitemapConfigurationService.cs b/src/SeoToolkit.Umbraco.Sitemap.Core/Config/SitemapConfigurationService.cs
index 6c8d84dd..08d21b35 100644
--- a/src/SeoToolkit.Umbraco.Sitemap.Core/Config/SitemapConfigurationService.cs
+++ b/src/SeoToolkit.Umbraco.Sitemap.Core/Config/SitemapConfigurationService.cs
@@ -23,6 +23,7 @@ public override SitemapConfig GetSettings()
                 ChangeFrequencyFieldAlias = settings.ChangeFrequencyFieldAlias,
                 PriorityFieldAlias = settings.PriorityFieldAlias,
                 ReturnContentType = settings.ReturnContentType,
+                LastModifiedFormat = settings.LastModifiedFormat,
                 DisabledModules = settings.DisabledModules
             };
         }