diff --git a/content/shared/public/nsCSSKeywordList.h b/content/shared/public/nsCSSKeywordList.h
index 08fcbba5e108..e7297bc7c903 100644
--- a/content/shared/public/nsCSSKeywordList.h
+++ b/content/shared/public/nsCSSKeywordList.h
@@ -76,6 +76,7 @@ CSS_KEY(-moz-bg-outset, _moz_bg_outset)
 CSS_KEY(-moz-box, _moz_box)
 CSS_KEY(-moz-bulletinboard, _moz_bulletinboard)
 CSS_KEY(-moz-button, _moz_button)
+CSS_KEY(-moz-buttondefault, _moz_buttondefault)
 CSS_KEY(-moz-cell, _moz_cell)
 CSS_KEY(-moz-center, _moz_center)
 CSS_KEY(-moz-cjk-earthly-branch, _moz_cjk_earthly_branch)
diff --git a/content/shared/src/nsCSSProps.cpp b/content/shared/src/nsCSSProps.cpp
index 6a1a70358a3f..1d38ea7d6359 100644
--- a/content/shared/src/nsCSSProps.cpp
+++ b/content/shared/src/nsCSSProps.cpp
@@ -351,6 +351,7 @@ const PRInt32 nsCSSProps::kColorKTable[] = {
   eCSSKeyword_window, nsILookAndFeel::eColor_window,
   eCSSKeyword_windowframe, nsILookAndFeel::eColor_windowframe,
   eCSSKeyword_windowtext, nsILookAndFeel::eColor_windowtext,
+  eCSSKeyword__moz_buttondefault, nsILookAndFeel::eColor__moz_buttondefault,
   eCSSKeyword__moz_field, nsILookAndFeel::eColor__moz_field,
   eCSSKeyword__moz_fieldtext, nsILookAndFeel::eColor__moz_fieldtext,
   eCSSKeyword__moz_dialog, nsILookAndFeel::eColor__moz_dialog,
diff --git a/layout/style/nsCSSKeywordList.h b/layout/style/nsCSSKeywordList.h
index 08fcbba5e108..e7297bc7c903 100644
--- a/layout/style/nsCSSKeywordList.h
+++ b/layout/style/nsCSSKeywordList.h
@@ -76,6 +76,7 @@ CSS_KEY(-moz-bg-outset, _moz_bg_outset)
 CSS_KEY(-moz-box, _moz_box)
 CSS_KEY(-moz-bulletinboard, _moz_bulletinboard)
 CSS_KEY(-moz-button, _moz_button)
+CSS_KEY(-moz-buttondefault, _moz_buttondefault)
 CSS_KEY(-moz-cell, _moz_cell)
 CSS_KEY(-moz-center, _moz_center)
 CSS_KEY(-moz-cjk-earthly-branch, _moz_cjk_earthly_branch)
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index 6a1a70358a3f..1d38ea7d6359 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -351,6 +351,7 @@ const PRInt32 nsCSSProps::kColorKTable[] = {
   eCSSKeyword_window, nsILookAndFeel::eColor_window,
   eCSSKeyword_windowframe, nsILookAndFeel::eColor_windowframe,
   eCSSKeyword_windowtext, nsILookAndFeel::eColor_windowtext,
+  eCSSKeyword__moz_buttondefault, nsILookAndFeel::eColor__moz_buttondefault,
   eCSSKeyword__moz_field, nsILookAndFeel::eColor__moz_field,
   eCSSKeyword__moz_fieldtext, nsILookAndFeel::eColor__moz_fieldtext,
   eCSSKeyword__moz_dialog, nsILookAndFeel::eColor__moz_dialog,