diff --git a/sources/titleblock/qettemplateeditor.cpp b/sources/titleblock/qettemplateeditor.cpp
index 9dd025132..3a316f15b 100644
--- a/sources/titleblock/qettemplateeditor.cpp
+++ b/sources/titleblock/qettemplateeditor.cpp
@@ -776,7 +776,20 @@ bool QETTitleBlockTemplateEditor::saveAs(const TitleBlockTemplateLocation &locat
 	elmt.setAttribute("name", location.name());
 	doc.appendChild(elmt);
 
-	collection -> setTemplateXmlDescription(location.name(), elmt);
+	if (!collection -> setTemplateXmlDescription(location.name(), elmt)) {
+			// Report the failure instead of marking the template "saved"
+			// regardless (bugtracker #251) -- this return value used to
+			// be discarded here.
+		QET::QetMessageBox::critical(
+			this,
+			tr("Erreur", "message box title"),
+			tr(
+				"Impossible d'enregistrer le modèle « %1 ».",
+				"message box content - %1 is a title block template name"
+			).arg(location.name())
+		);
+		return(false);
+	}
 
 	opened_from_file_ = false;
 	location_ = location;
@@ -880,6 +893,21 @@ bool QETTitleBlockTemplateEditor::saveAs()
 	if (location.isValid()) {
 		return(saveAs(location));
 	}
+	if (!location.name().isEmpty()) {
+			// The name was rejected (e.g. contains a path separator or
+			// other filesystem-reserved character) rather than the user
+			// cancelling the dialog -- say so instead of silently doing
+			// nothing (bugtracker #251).
+		QET::QetMessageBox::critical(
+			this,
+			tr("Erreur", "message box title"),
+			tr(
+				"Le nom « %1 » n'est pas valide : il ne doit pas contenir "
+				"les caractères suivants : \\ / : * ? \" < > |",
+				"message box content - %1 is the rejected template name"
+			).arg(location.name())
+		);
+	}
 	return(false);
 }
 
diff --git a/sources/titleblock/templatelocation.cpp b/sources/titleblock/templatelocation.cpp
index 4387d6412..6f01ce591 100644
--- a/sources/titleblock/templatelocation.cpp
+++ b/sources/titleblock/templatelocation.cpp
@@ -92,7 +92,13 @@ void TitleBlockTemplateLocation::setName(const QString &name) {
 */
 bool TitleBlockTemplateLocation::isValid() const
 {
-	return(!name_.isEmpty());
+	// The name becomes (part of) a filename on disk (see
+	// TitleBlockTemplatesFilesCollection::toFileName()). A name containing
+	// a path separator or another filesystem-reserved character silently
+	// fails to save instead of erroring, because it turns into an
+	// unintended subpath rather than a plain filename (bugtracker #251).
+	static const QRegularExpression invalid_chars_re(QStringLiteral("[\\\\/:*?\"<>|]"));
+	return(!name_.isEmpty() && !name_.contains(invalid_chars_re));
 }
 
 /**