diff --git a/themes/classic/navigator/mac/tabbrowser.css b/themes/classic/navigator/mac/tabbrowser.css
new file mode 100644
index 00000000000..530303863ca
--- /dev/null
+++ b/themes/classic/navigator/mac/tabbrowser.css
@@ -0,0 +1,6 @@
+
+@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+
+tab[busy] {
+  list-style-image: url("chrome://global/skin/loading.gif");
+}
diff --git a/themes/classic/navigator/win/tabbrowser.css b/themes/classic/navigator/win/tabbrowser.css
new file mode 100644
index 00000000000..530303863ca
--- /dev/null
+++ b/themes/classic/navigator/win/tabbrowser.css
@@ -0,0 +1,6 @@
+
+@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+
+tab[busy] {
+  list-style-image: url("chrome://global/skin/loading.gif");
+}