Index: class.wp-styles.php
===================================================================
--- class.wp-styles.php	(revision 13228)
+++ class.wp-styles.php	(working copy)
@@ -68,10 +68,12 @@
 
 		$tag .= apply_filters( 'style_loader_tag', "<link rel='$rel' id='$handle-css' $title href='$href' type='text/css' media='$media' />\n", $handle );
 		if ( 'rtl' === $this->text_direction && isset($this->registered[$handle]->extra['rtl']) && $this->registered[$handle]->extra['rtl'] ) {
-			if ( is_bool( $this->registered[$handle]->extra['rtl'] ) )
-				$rtl_href = str_replace( '.css', '-rtl.css', $this->_css_href( $this->registered[$handle]->src , $ver, "$handle-rtl" ));
-			else
+			if ( is_bool( $this->registered[$handle]->extra['rtl'] ) ) {
+				$suffix = isset( $this->registered[$handle]->extra['suffix'] ) ? $this->registered[$handle]->extra['suffix'] : '';
+				$rtl_href = str_replace( "{$suffix}.css", "-rtl{$suffix}.css", $this->_css_href( $this->registered[$handle]->src , $ver, "$handle-rtl" ));
+			} else {
 				$rtl_href = $this->_css_href( $this->registered[$handle]->extra['rtl'], $ver, "$handle-rtl" );
+			}
 
 			$tag .= apply_filters( 'style_loader_tag', "<link rel='$rel' id='$handle-rtl-css' $title href='$rtl_href' type='text/css' media='$media' />\n", $handle );
 		}
Index: script-loader.php
===================================================================
--- script-loader.php	(revision 13237)
+++ script-loader.php	(working copy)
@@ -424,6 +424,8 @@
 	$styles->default_dirs = array('/wp-admin/');
 
 	$suffix = defined('SCRIPT_DEBUG') && SCRIPT_DEBUG ? '.dev' : '';
+	// Any stylesheets that don't have a .dev version for ltr or rtl
+	$no_suffix = array( 'farbtastic' );
 
 	$rtl_styles = array( 'wp-admin', 'global', 'colors', 'dashboard', 'ie', 'install', 'login', 'media', 'theme-editor', 'upload', 'widgets', 'press-this', 'plugin-install', 'farbtastic' );
 
@@ -432,7 +434,7 @@
 
 	$styles->add( 'wp-admin', "/wp-admin/css/wp-admin$suffix.css", array(), '20100217' );
 
-	$styles->add( 'ie', '/wp-admin/css/ie.css', array(), '20100108' );
+	$styles->add( 'ie', "/wp-admin/css/ie$suffix.css", array(), '20100108' );
 	$styles->add_data( 'ie', 'conditional', 'lte IE 7' );
 
 	// Register "meta" stylesheet for admin colors. All colors-* style sheets should have the same version string.
@@ -460,8 +462,11 @@
 	$styles->add( 'jcrop', '/wp-includes/js/jcrop/jquery.Jcrop.css', array(), '0.9.8' );
 	$styles->add( 'imgareaselect', '/wp-includes/js/imgareaselect/imgareaselect.css', array(), '0.9.1' );
 
-	foreach ( $rtl_styles as $rtl_style )
+	foreach ( $rtl_styles as $rtl_style ) {
 		$styles->add_data( $rtl_style, 'rtl', true );
+		if ( $suffix && ! in_array( $rtl_style, $no_suffix ) )
+			$styles->add_data( $rtl_style, 'suffix', $suffix );
+	}
 }
 
 /**