diff --git a/src/BufferParams.cpp b/src/BufferParams.cpp
index 98376c5e5d..e4d241d56c 100644
--- a/src/BufferParams.cpp
+++ b/src/BufferParams.cpp
@@ -529,7 +529,11 @@ string const BufferParams::readToken(Lexer & lex, string const & token,
 		paragraph_separation = parseptranslator().find(parsep);
 	} else if (token == "\\defskip") {
 		lex.next();
-		pimpl_->defskip = VSpace(lex.getString());
+		string defskip = lex.getString();
+		if (defskip == "defskip")
+			// this is invalid
+			defskip = "medskip";
+		pimpl_->defskip = VSpace(defskip);
 	} else if (token == "\\quotes_language") {
 		string quotes_lang;
 		lex >> quotes_lang;
diff --git a/src/frontends/qt4/GuiDocument.cpp b/src/frontends/qt4/GuiDocument.cpp
index 3ea5e1aa83..6f020c3acd 100644
--- a/src/frontends/qt4/GuiDocument.cpp
+++ b/src/frontends/qt4/GuiDocument.cpp
@@ -2033,7 +2033,9 @@ void GuiDocument::useClassDefaults()
 
 bool GuiDocument::isValid()
 {
-	return validate_listings_params().empty();
+	return (validate_listings_params().empty() &&
+		(textLayoutModule->skipCO->currentIndex() != 3 ||
+		 !textLayoutModule->skipLE->text().isEmpty()));
 }