diff --git a/src/AbstractWebApplication.php b/src/AbstractWebApplication.php
index 23464c00..8b69f0b7 100644
--- a/src/AbstractWebApplication.php
+++ b/src/AbstractWebApplication.php
@@ -817,7 +817,11 @@ protected function detectRequestUri()
         } else {
             // If not in "Apache Mode" we will assume that we are in an IIS environment and proceed.
             // IIS uses the SCRIPT_NAME variable instead of a REQUEST_URI variable... thanks, MS
-            $uri .= $this->input->server->getString('SCRIPT_NAME');
+            $scriptname = $this->input->server->getString('SCRIPT_NAME');
+            if (!str_starts_with($scriptname, '/') && !str_ends_with($uri, '/')) {
+                $uri .= '/';
+            }
+            $uri .= $scriptname;
             $queryHost = $this->input->server->getString('QUERY_STRING', '');
 
             // If the QUERY_STRING variable exists append it to the URI string.