diff --git a/wp-admin/includes/image.php b/wp-admin/includes/image.php
index 1781716998..96c301457f 100644
--- a/wp-admin/includes/image.php
+++ b/wp-admin/includes/image.php
@@ -150,7 +150,7 @@ function wp_generate_attachment_metadata( $attachment_id, $file ) {
 		$metadata['hwstring_small'] = "height='$uheight' width='$uwidth'";
 		$metadata['file'] = $file;
 
-		$max = apply_filters( 'wp_thumbnail_creation_size_limit', 3 * 1024 * 1024, $attachment_id, $file );
+		$max = apply_filters( 'wp_thumbnail_creation_size_limit', abs( inval( WP_MEMORY_LIMIT ) ) * 1024 * 1024, $attachment_id, $file );
 
 		if ( $max < 0 || $metadata['width'] * $metadata['height'] < $max ) {
 			$max_side = apply_filters( 'wp_thumbnail_max_side_length', 128, $attachment_id, $file );
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 87d7eb138b..05e0720099 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -1070,7 +1070,7 @@ function wp_unique_filename( $dir, $filename, $unique_filename_callback = NULL )
 
 	// separate the filename into a name and extension
 	$info = pathinfo($filename);
-	$ext = $info['extension'];
+	$ext = strtolower( $info['extension'] );
 	$name = basename($filename, ".{$ext}");
 
 	// Increment the file number until we have a unique file to save in $dir. Use $override['unique_filename_callback'] if supplied.