diff --git a/sources/diagramcontext.cpp b/sources/diagramcontext.cpp
index 4e4f0d205..5137a7bf5 100644
--- a/sources/diagramcontext.cpp
+++ b/sources/diagramcontext.cpp
@@ -151,8 +151,8 @@ bool DiagramContext::operator!=(const DiagramContext &dc) const
 void DiagramContext::toXml(QDomElement &e, const QString &tag_name) const
 {
 	foreach (QString key, keys()) {
-		if ((tag_name == "elementInformation") &&
-			(m_content[key].toString().trimmed().isEmpty())) {
+		const QString raw = m_content[key].toString();
+		if ((tag_name == "elementInformation") && raw.trimmed().isEmpty()) {
 			continue;
 		}
 		QDomElement property = e.ownerDocument().createElement(tag_name);
@@ -161,7 +161,15 @@ void DiagramContext::toXml(QDomElement &e, const QString &tag_name) const
 		property.removeAttribute("name");
 		property.setAttribute("show", m_content_show[key]);
 		property.setAttribute("name", key);
-		QDomText value = e.ownerDocument().createTextNode(m_content[key].toString().trimmed());
+		// Trim stray leading/trailing whitespace around real content, but
+		// not a value that IS whitespace: unconditionally trimming an
+		// all-whitespace string collapses it to "", which is silently
+		// indistinguishable from a value that was never set. A title-block
+		// custom variable set to a single space -- a workaround for #973,
+		// where an unset variable renders as its own literal placeholder --
+		// would otherwise vanish on the very next save.
+		const QString stored = raw.trimmed().isEmpty() ? raw : raw.trimmed();
+		QDomText value = e.ownerDocument().createTextNode(stored);
 		property.appendChild(value);
 		e.appendChild(property);
 	}
diff --git a/sources/qetproject.cpp b/sources/qetproject.cpp
index 49b4a6520..af0f00b25 100644
--- a/sources/qetproject.cpp
+++ b/sources/qetproject.cpp
@@ -334,7 +334,18 @@ QETProject::ProjectState QETProject::openFile(QFile *file)
 		//file without a persisted uuid derives its uuid from them.
 	const QByteArray content = file->readAll();
 	QDomDocument xml_project;
-	if (!xml_project.setContent(content))
+	// PreserveSpacingOnlyNodes: without it, a text node that is entirely
+	// whitespace -- e.g. a title-block custom variable deliberately set to
+	// a single space, the only way to give it a value other than blank
+	// (bugtracker #973) -- is silently dropped by Qt's default parsing,
+	// and QDomElement::text() then returns "" for it exactly as if it had
+	// never been set. Confirmed in isolation: <a> </a> parses to text()=="",
+	// this option makes it text()==" ". Every place in this codebase that
+	// walks a QDomNode's children already filters on isElement() (see
+	// QET::findInDomElement()), so the extra whitespace-only text nodes
+	// this keeps around are inert everywhere but the two elements that
+	// call .text() on themselves -- which is exactly where the bug was.
+	if (!xml_project.setContent(content, QDomDocument::ParseOption::PreserveSpacingOnlyNodes))
 	{
 		if(opened_here) {
 			file->close();