diff --git a/class.photon.php b/class.photon.php
index 64a7e61ddfb4d..efd9a48f189b7 100644
--- a/class.photon.php
+++ b/class.photon.php
@@ -720,7 +720,7 @@ public function filter_srcset_array( $sources, $size_array, $image_src, $image_m
 					);
 			} // foreach ( $multipliers as $multiplier )
 			if ( is_array( $newsources ) ) {
-				$sources = array_merge( $sources, $newsources );
+				$sources = array_replace( $sources, $newsources );
 			}
 		} // if ( isset( $image_meta['width'] ) && isset( $image_meta['file'] ) )