--- a/browser/themes/shared/identity-block/identity-block.inc.css
+++ b/browser/themes/shared/identity-block/identity-block.inc.css
@@ -110,20 +110,21 @@
 
 #identity-box[sharing] > #sharing-icon {
   display: -moz-box;
   animation-delay: -1.5s;
 }
 
 #identity-box[sharing] > #identity-icon,
 #sharing-icon {
-  animation: 3s linear pulse infinite;
+  animation: 3s linear identity-box-sharing-icon-pulse infinite;
 }
 
-@keyframes pulse {
+/* This should remain identical to tab-sharing-icon-pulse in tabs.inc.css */
+@keyframes identity-box-sharing-icon-pulse {
   0%, 16.66%, 83.33%, 100% {
     opacity: 0;
   }
   33.33%, 66.66% {
     opacity: 1;
   }
 }
 

--- a/browser/themes/shared/tabs.inc.css
+++ b/browser/themes/shared/tabs.inc.css
@@ -86,20 +86,21 @@
 }
 
 .tab-icon-image {
   list-style-image: url("chrome://mozapps/skin/places/defaultFavicon.png");
 }
 
 .tab-icon-image[sharing]:not([selected]),
 .tab-sharing-icon-overlay {
-  animation: 3s linear pulse infinite;
+  animation: 3s linear tab-sharing-icon-pulse infinite;
 }
 
-@keyframes pulse {
+/* This should remain identical to identity-box-sharing-icon-pulse in identity-block.inc.css */
+@keyframes tab-sharing-icon-pulse {
   0%, 16.66%, 83.33%, 100% {
     opacity: 0;
   }
   33.33%, 66.66% {
     opacity: 1;
   }
 }