--- a/browser/themes/shared/toolbarbutton-icons.inc.css
+++ b/browser/themes/shared/toolbarbutton-icons.inc.css
@@ -12,21 +12,29 @@
 toolbar[brighttext] :-moz-any(@primaryToolbarButtons@) {
   fill: var(--toolbarbutton-icon-fill-inverted);
 }
 
 #back-button {
   list-style-image: url("chrome://browser/skin/back-large.svg");
 }
 
+#back-button:-moz-locale-dir(rtl) > .toolbarbutton-icon {
+  transform: scaleX(-1);
+}
+
 #forward-button {
   list-style-image: url("chrome://browser/skin/forward.svg");
 }
 
 %ifdef MOZ_PHOTON_THEME
+#forward-button:-moz-locale-dir(rtl) > .toolbarbutton-icon {
+  transform: scaleX(-1);
+}
+
 #reload-button {
   list-style-image: url("chrome://browser/skin/reload.svg");
 }
 
 #stop-button {
   list-style-image: url("chrome://browser/skin/stop.svg");
 }
 %endif

--- a/browser/themes/shared/toolbarbuttons.inc.css
+++ b/browser/themes/shared/toolbarbuttons.inc.css
@@ -357,20 +357,16 @@ toolbar[brighttext] .toolbarbutton-1 > .
 #back-button > .toolbarbutton-icon {
 %ifdef MOZ_PHOTON_THEME
   border-color: var(--backbutton-border-color) !important;
 %endif
   border-radius: 10000px !important;
   padding: 7px !important;
 }
 
-#back-button:-moz-locale-dir(rtl) > .toolbarbutton-icon {
-  transform: scaleX(-1);
-}
-
 %ifdef MOZ_PHOTON_THEME
 #back-button:not(:hover):not(:active):not([open=true]) > .toolbarbutton-icon,
 #back-button[disabled=true] > .toolbarbutton-icon {
   background: var(--backbutton-background) !important;
 }
 %endif
 
 /* bookmarks menu-button */