diff --git a/content/html/content/src/nsHTMLAtomList.h b/content/html/content/src/nsHTMLAtomList.h
index f0f182446fd..7110810e84c 100644
--- a/content/html/content/src/nsHTMLAtomList.h
+++ b/content/html/content/src/nsHTMLAtomList.h
@@ -290,3 +290,5 @@ HTML_ATOM(wrappedFramePseudo, ":wrapped-frame")
 HTML_ATOM(zindex, "zindex")
 HTML_ATOM(z_index, "z-index")
 
+HTML_ATOM(moz_tristate, "moz-tristate")
+HTML_ATOM(moz_tristatevalue, "moz-tristatevalue")
diff --git a/content/shared/public/nsHTMLAtomList.h b/content/shared/public/nsHTMLAtomList.h
index f0f182446fd..7110810e84c 100644
--- a/content/shared/public/nsHTMLAtomList.h
+++ b/content/shared/public/nsHTMLAtomList.h
@@ -290,3 +290,5 @@ HTML_ATOM(wrappedFramePseudo, ":wrapped-frame")
 HTML_ATOM(zindex, "zindex")
 HTML_ATOM(z_index, "z-index")
 
+HTML_ATOM(moz_tristate, "moz-tristate")
+HTML_ATOM(moz_tristatevalue, "moz-tristatevalue")
diff --git a/layout/html/base/src/nsHTMLAtomList.h b/layout/html/base/src/nsHTMLAtomList.h
index f0f182446fd..7110810e84c 100644
--- a/layout/html/base/src/nsHTMLAtomList.h
+++ b/layout/html/base/src/nsHTMLAtomList.h
@@ -290,3 +290,5 @@ HTML_ATOM(wrappedFramePseudo, ":wrapped-frame")
 HTML_ATOM(zindex, "zindex")
 HTML_ATOM(z_index, "z-index")
 
+HTML_ATOM(moz_tristate, "moz-tristate")
+HTML_ATOM(moz_tristatevalue, "moz-tristatevalue")