diff --git a/content/shared/public/nsLayoutAtomList.h b/content/shared/public/nsLayoutAtomList.h
index 6bf11de1b02..30e8fd2fd83 100644
--- a/content/shared/public/nsLayoutAtomList.h
+++ b/content/shared/public/nsLayoutAtomList.h
@@ -68,6 +68,7 @@ LAYOUT_ATOM(popupList, "Popup-list")
 LAYOUT_ATOM(canvasPseudo, ":canvas")
 LAYOUT_ATOM(commentTagName, "__moz_comment")
 LAYOUT_ATOM(dummyOptionPseudo, ":-moz-dummy-option")
+LAYOUT_ATOM(optionSelectedPseudo, ":-moz-option-selected")
 LAYOUT_ATOM(textTagName, "__moz_text")
 LAYOUT_ATOM(pagePseudo, ":-moz-page")
 LAYOUT_ATOM(pageSequencePseudo, ":-moz-page-sequence")
diff --git a/layout/base/nsLayoutAtomList.h b/layout/base/nsLayoutAtomList.h
index 6bf11de1b02..30e8fd2fd83 100644
--- a/layout/base/nsLayoutAtomList.h
+++ b/layout/base/nsLayoutAtomList.h
@@ -68,6 +68,7 @@ LAYOUT_ATOM(popupList, "Popup-list")
 LAYOUT_ATOM(canvasPseudo, ":canvas")
 LAYOUT_ATOM(commentTagName, "__moz_comment")
 LAYOUT_ATOM(dummyOptionPseudo, ":-moz-dummy-option")
+LAYOUT_ATOM(optionSelectedPseudo, ":-moz-option-selected")
 LAYOUT_ATOM(textTagName, "__moz_text")
 LAYOUT_ATOM(pagePseudo, ":-moz-page")
 LAYOUT_ATOM(pageSequencePseudo, ":-moz-page-sequence")
diff --git a/layout/base/public/nsLayoutAtomList.h b/layout/base/public/nsLayoutAtomList.h
index 6bf11de1b02..30e8fd2fd83 100644
--- a/layout/base/public/nsLayoutAtomList.h
+++ b/layout/base/public/nsLayoutAtomList.h
@@ -68,6 +68,7 @@ LAYOUT_ATOM(popupList, "Popup-list")
 LAYOUT_ATOM(canvasPseudo, ":canvas")
 LAYOUT_ATOM(commentTagName, "__moz_comment")
 LAYOUT_ATOM(dummyOptionPseudo, ":-moz-dummy-option")
+LAYOUT_ATOM(optionSelectedPseudo, ":-moz-option-selected")
 LAYOUT_ATOM(textTagName, "__moz_text")
 LAYOUT_ATOM(pagePseudo, ":-moz-page")
 LAYOUT_ATOM(pageSequencePseudo, ":-moz-page-sequence")