Index: includes/GlobalFunctions.php
===================================================================
--- includes/GlobalFunctions.php	(revision 19274)
+++ includes/GlobalFunctions.php	(working copy)
@@ -230,7 +230,7 @@
 			$forward .= ' anon';
 		$log = sprintf( "%s\t%04.3f\t%s\n",
 		  gmdate( 'YmdHis' ), $elapsed,
-		  urldecode( $_SERVER['REQUEST_URI'] . $forward ) );
+		  urldecode( $wgRequest->getRequestURL() . $forward ) );
 		if ( '' != $wgDebugLogFile && ( $wgRequest->getVal('action') != 'raw' || $wgDebugRawPage ) ) {
 			error_log( $log . $prof, 3, $wgDebugLogFile );
 		}
Index: includes/WebRequest.php
===================================================================
--- includes/WebRequest.php	(revision 19274)
+++ includes/WebRequest.php	(working copy)
@@ -314,7 +314,20 @@
 	 * @return string
 	 */
 	function getRequestURL() {
-		$base = $_SERVER['REQUEST_URI'];
+		if( isset( $_SERVER['REQUEST_URI'] ) ) {
+			$base = $_SERVER['REQUEST_URI'];
+		} elseif( isset( $_SERVER['SCRIPT_NAME'] ) ) {
+			// Probably IIS; doesn't set REQUEST_URI
+			$base = $_SERVER['SCRIPT_NAME'];
+			if( isset( $_SERVER['QUERY_STRING'] ) && $_SERVER['QUERY_STRING'] != '' ) {
+				$base .= '?' . $_SERVER['QUERY_STRING'];
+			}
+		} else {
+			// This shouldn't happen!
+			throw new MWException( "Web server doesn't provide either " .
+				"REQUEST_URI or SCRIPT_NAME. Report details of your " .
+				"web server configuration to http://bugzilla.wikimedia.org/" );
+		}
 		if( $base{0} == '/' ) {
 			return $base;
 		} else {
Index: includes/Wiki.php
===================================================================
--- includes/Wiki.php	(revision 19274)
+++ includes/Wiki.php	(working copy)
@@ -118,7 +118,7 @@
 	 * Initialize the object to be known as $wgArticle for special cases
 	 */
 	function initializeSpecialCases ( &$title, &$output, $request ) {
-
+		global $wgRequest;
 		wfProfileIn( 'MediaWiki::initializeSpecialCases' );
 		
 		$search = $this->getVal('Search');
@@ -151,8 +151,7 @@
 			$targetUrl = $title->getFullURL();
 			// Redirect to canonical url, make it a 301 to allow caching
 			global $wgServer, $wgUsePathInfo;
-			if( isset( $_SERVER['REQUEST_URI'] ) &&
-				$targetUrl == $wgServer . $_SERVER['REQUEST_URI'] ) {
+			if( $targetUrl == $wgRequest->getFullRequestURL() ) {
 				$message = "Redirect loop detected!\n\n" .
 					"This means the wiki got confused about what page was " .
 					"requested; this sometimes happens when moving a wiki " .
Index: includes/Skin.php
===================================================================
--- includes/Skin.php	(revision 19274)
+++ includes/Skin.php	(working copy)
@@ -782,13 +782,6 @@
 	function printableLink() {
 		global $wgOut, $wgFeedClasses, $wgRequest;
 
-		$baseurl = $_SERVER['REQUEST_URI'];
-		if( strpos( '?', $baseurl ) == false ) {
-			$baseurl .= '?';
-		} else {
-			$baseurl .= '&';
-		}
-		$baseurl = htmlspecialchars( $baseurl );
 		$printurl = $wgRequest->escapeAppendQuery( 'printable=yes' );
 
 		$s = "<a href=\"$printurl\">" . wfMsg( 'printableversion' ) . '</a>';
Index: includes/Exception.php
===================================================================
--- includes/Exception.php	(revision 19274)
+++ includes/Exception.php	(working copy)
@@ -54,10 +54,11 @@
 	}
 	
 	function getLogMessage() {
+		global $wgRequest;
 		$file = $this->getFile();
 		$line = $this->getLine();
 		$message = $this->getMessage();
-		return "{$_SERVER['REQUEST_URI']} Exception from line $line of $file: $message";
+		return $wgRequest->getRequestURL() . " Exception from line $line of $file: $message";
 	}
 	
 	function reportHTML() {