diff --git a/gfx/thebes/gfxMacPlatformFontList.mm b/gfx/thebes/gfxMacPlatformFontList.mm
index 92f882b3b6d3..2e4a6b644a44 100644
--- a/gfx/thebes/gfxMacPlatformFontList.mm
+++ b/gfx/thebes/gfxMacPlatformFontList.mm
@@ -814,9 +814,14 @@ void gfxSingleFaceMacFontFamily::ReadOtherFamilyNames(gfxPlatformFontList* aPlat
 // under /System/Fonts. Whether they're exposed in the font list by default
 // depends on the SDK used; when built with SDK 10.15, they're absent. So
 // we explicitly activate them to be sure they'll be available.
+#if __MAC_OS_X_VERSION_MAX_ALLOWED < 101500
+static const nsLiteralCString kLangFontsDirs[] = {
+    "/Library/Application Support/Apple/Fonts/Language Support"_ns};
+#else
 static const nsLiteralCString kLangFontsDirs[] = {
     "/Library/Application Support/Apple/Fonts/Language Support"_ns,
     "/System/Library/Fonts/Supplemental"_ns};
+#endif
 
 gfxMacPlatformFontList::gfxMacPlatformFontList()
     : gfxPlatformFontList(false), mDefaultFont(nullptr), mUseSizeSensitiveSystemFont(false) {