diff --git a/themes/classic/global/mac/autocomplete.css b/themes/classic/global/mac/autocomplete.css
index d3363eac63f..4573f042814 100644
--- a/themes/classic/global/mac/autocomplete.css
+++ b/themes/classic/global/mac/autocomplete.css
@@ -26,7 +26,6 @@
   ======================================================================= */
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
-@namespace html url("http://www.w3.org/1999/xhtml");
 
 /* ::::: autocomplete ::::: */
 
diff --git a/themes/classic/global/mac/button.css b/themes/classic/global/mac/button.css
index f50cb8621c4..aed427db753 100644
--- a/themes/classic/global/mac/button.css
+++ b/themes/classic/global/mac/button.css
@@ -146,4 +146,4 @@ button.plain {
 
 .close-button > .toolbarbutton-text {
   display: none;
-}
\ No newline at end of file
+}
diff --git a/themes/classic/global/mac/nativescrollbars.css b/themes/classic/global/mac/nativescrollbars.css
index 5b4e8078f32..6d48c8b5cdb 100644
--- a/themes/classic/global/mac/nativescrollbars.css
+++ b/themes/classic/global/mac/nativescrollbars.css
@@ -26,6 +26,7 @@
   ======================================================================= */
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+@namespace html url("http://www.w3.org/1999/xhtml"); /* namespace for HTML elements */
 
 /* ::::: scrollbar ::::: */
 
diff --git a/themes/classic/global/mac/xulscrollbars.css b/themes/classic/global/mac/xulscrollbars.css
index 0521ca54ce4..ab45fdd3c2e 100644
--- a/themes/classic/global/mac/xulscrollbars.css
+++ b/themes/classic/global/mac/xulscrollbars.css
@@ -26,6 +26,7 @@
   ======================================================================= */
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+@namespace html url("http://www.w3.org/1999/xhtml"); /* namespace for HTML elements */
 
 /* ::::: scrollbar ::::: */
 
diff --git a/themes/classic/global/unix/autocomplete.css b/themes/classic/global/unix/autocomplete.css
index 594d0fcd160..7c6a41abc60 100644
--- a/themes/classic/global/unix/autocomplete.css
+++ b/themes/classic/global/unix/autocomplete.css
@@ -27,7 +27,6 @@
   ======================================================================= */
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
-@namespace html url("http://www.w3.org/1999/xhtml");
 
 /* ::::: autocomplete ::::: */
 
diff --git a/themes/classic/global/win/autocomplete.css b/themes/classic/global/win/autocomplete.css
index afd6d131635..56cca7efdb3 100644
--- a/themes/classic/global/win/autocomplete.css
+++ b/themes/classic/global/win/autocomplete.css
@@ -26,7 +26,6 @@
   ======================================================================= */
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
-@namespace html url("http://www.w3.org/1999/xhtml");
 
 /* ::::: autocomplete ::::: */