diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 28725e7547..2ee2be8a90 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -2365,7 +2365,7 @@ function wp_get_image_mime( $file ) {
 	 * we assume the file could not be validated.
 	 */
 	try {
-		if ( ! is_callable( 'exif_imagetype' ) ) {
+		if ( is_callable( 'exif_imagetype' ) ) {
 			$mime = image_type_to_mime_type( exif_imagetype( $file ) );
 		} elseif ( function_exists( 'getimagesize' ) ) {
 			$imagesize = getimagesize( $file );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index eea3836787..eb083f7399 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-39848';
+$wp_version = '4.8-alpha-39850';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.