diff --git a/lib/languages b/lib/languages
index d32118ae2f..04b3cfed14 100644
--- a/lib/languages
+++ b/lib/languages
@@ -665,6 +665,7 @@ End
 Language estonian
 	GuiName          "Estonian"
 	BabelName        estonian
+	BabelOptFormat   modifier
 	PolyglossiaName  estonian
 	XindyName        estonian
 	QuoteStyle       german
@@ -901,6 +902,7 @@ End
 Language icelandic
 	GuiName          "Icelandic"
 	BabelName        icelandic
+	BabelOptFormat   modifier
 	PolyglossiaName  icelandic
 	XindyName        icelandic
 	QuoteStyle       german
@@ -1065,6 +1067,7 @@ End
 Language latvian
 	GuiName          "Latvian"
 	BabelName        latvian
+	BabelOptFormat   modifier
 	PolyglossiaName  latvian
 	XindyName        latvian
 	QuoteStyle       german
@@ -1378,6 +1381,7 @@ Language serbian
 	GuiName          "Serbian"
 	HasGuiSupport    true
 	BabelName        serbianc
+	BabelOptFormat   modifier
 	PolyglossiaName  serbian
 	PolyglossiaOpts  "script=Cyrillic"
 	XindyName        serbian
@@ -1625,6 +1629,7 @@ End
 Language vietnamese
 	GuiName          "Vietnamese"
 	BabelName        vietnamese
+	BabelOptFormat   modifier
 	PolyglossiaName  vietnamese
 	XindyName        vietnamese
 	QuoteStyle       english