diff --git a/Dnn.AdminExperience/Dnn.PersonaBar.Extensions/Components/Themes/ThemesController.cs b/Dnn.AdminExperience/Dnn.PersonaBar.Extensions/Components/Themes/ThemesController.cs
index 6de1ab9a040..9b5b31cd2a9 100644
--- a/Dnn.AdminExperience/Dnn.PersonaBar.Extensions/Components/Themes/ThemesController.cs
+++ b/Dnn.AdminExperience/Dnn.PersonaBar.Extensions/Components/Themes/ThemesController.cs
@@ -373,7 +373,7 @@ internal static string CreateThumbnail(string strImage)
             var imageFileName = Path.GetFileName(strImage);
             if (string.IsNullOrEmpty(imageFileName) || imageFileName.StartsWith("thumbnail_"))
             {
-                strImage = Globals.ApplicationPath + "/" + strImage.Substring(strImage.IndexOf("portals\\"));
+                strImage = strImage.Substring(Globals.ApplicationMapPath.Length);
                 strImage = strImage.Replace("\\", "/");
                 return strImage;
             }
@@ -439,7 +439,7 @@ internal static string CreateThumbnail(string strImage)
                 }
             }
 
-            strThumbnail = Globals.ApplicationPath + "/" + strThumbnail.Substring(strThumbnail.IndexOf("portals\\"));
+            strThumbnail = strThumbnail.Substring(Globals.ApplicationMapPath.Length);
             strThumbnail = strThumbnail.Replace("\\", "/");
 
             // return thumbnail filename