diff --git a/floating_block.js b/floating_block.js
index 4541ec50784ddf3dcf48a54a397fb9b1fbcc1f6d..3c5834073be1aea418ed0e240c2ec04875527f30 100644
--- a/floating_block.js
+++ b/floating_block.js
@@ -144,7 +144,7 @@ Drupal.blockFloatTracker = function (blockInfo) {
       left:  blockInfo.original_offset.left + 'px',
       position: 'fixed',
       top: topPosition + 'px'
-    });
+    }).addClass('floating-block-active');
 
     blockInfo.floating = true;
   }
@@ -163,7 +163,7 @@ Drupal.blockFloatResetPosition = function (block, blockInfo) {
       left: blockInfo.original_css.left,
       position: blockInfo.original_css.position,
       top: blockInfo.original_css.top
-    });
+    }).removeClass('floating-block-active');
     blockInfo.floating = false;
   }
 }