diff --git a/content/base/src/nsGkAtomList.h b/content/base/src/nsGkAtomList.h
index 753ec52817c2..aef0b08497d0 100644
--- a/content/base/src/nsGkAtomList.h
+++ b/content/base/src/nsGkAtomList.h
@@ -2047,13 +2047,6 @@ GK_ATOM(windows_theme_royale, "windows-theme-royale")
 GK_ATOM(windows_theme_zune, "windows-theme-zune")
 GK_ATOM(windows_theme_generic, "windows-theme-generic")
 
-// windows version info selector metrics, helpful in removing ambiguity
-// in theme selectors.
-GK_ATOM(windows_version_xp, "windows-version-xp")
-GK_ATOM(windows_version_vista, "windows-version-vista")
-GK_ATOM(windows_version_win7, "windows-version-win7")
-GK_ATOM(windows_version_win8, "windows-version-win8")
-
 // And the same again, as media query keywords.
 GK_ATOM(_moz_color_picker_available, "-moz-color-picker-available")
 GK_ATOM(_moz_scrollbar_start_backward, "-moz-scrollbar-start-backward")
diff --git a/layout/style/nsCSSRuleProcessor.cpp b/layout/style/nsCSSRuleProcessor.cpp
index 18f0c19b3d17..52e79902e382 100644
--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -1243,27 +1243,6 @@ InitSystemMetrics()
   }
 #endif
 
-  // os version metrics, currently only defined for Windows.
-  if (NS_SUCCEEDED(
-        LookAndFeel::GetInt(LookAndFeel::eIntID_OperatingSystemVersionIdentifier,
-                            &metricResult))) {
-    switch(metricResult) {
-      case LookAndFeel::eOperatingSystemVersion_WindowsXP:
-        sSystemMetrics->AppendElement(nsGkAtoms::windows_version_xp);
-        break;
-      case LookAndFeel::eOperatingSystemVersion_WindowsVista:
-        sSystemMetrics->AppendElement(nsGkAtoms::windows_version_vista);
-        break;
-      case LookAndFeel::eOperatingSystemVersion_Windows7:
-        sSystemMetrics->AppendElement(nsGkAtoms::windows_version_win7);
-        break;
-      case LookAndFeel::eOperatingSystemVersion_Windows8:
-        sSystemMetrics->AppendElement(nsGkAtoms::windows_version_win8);
-        break;
-      // don't add anything for future versions
-    }
-  }
-
   return true;
 }