diff --git a/include/core/validator.h b/include/core/validator.h
index 2419de5d..46b916ce 100644
--- a/include/core/validator.h
+++ b/include/core/validator.h
@@ -34,7 +34,7 @@ public:
     QString prefix() const { return m_prefix; }
     void setPrefix(const QString &prefix);
 
-    bool isValid(QString &input) const;
+    bool isValid(const QString &input) const;
 
 private:
     QString m_prefix;
diff --git a/include/project.h b/include/project.h
index d393fbbb..23cd0f57 100644
--- a/include/project.h
+++ b/include/project.h
@@ -131,7 +131,7 @@ public:
     Layout *createNewLayout(const Layout::Settings &layoutSettings, const Layout* toDuplicate = nullptr);
     Tileset *createNewTileset(QString name, bool secondary, bool checkerboardFill);
     bool isIdentifierUnique(const QString &identifier) const;
-    bool isValidNewIdentifier(QString identifier) const;
+    bool isValidNewIdentifier(const QString &identifier) const;
     QString toUniqueIdentifier(const QString &identifier) const;
     QString getProjectTitle() const;
     QString getNewHealLocationName(const Map* map) const;
@@ -147,7 +147,7 @@ public:
     QString getDefaultSpeciesIconPath(const QString &species);
     QPixmap getSpeciesIcon(const QString &species);
 
-    void addNewMapsec(const QString &idName);
+    bool addNewMapsec(const QString &idName, const QString &displayName = QString());
     void removeMapsec(const QString &idName);
     QString getMapsecDisplayName(const QString &idName) const { return this->mapSectionDisplayNames.value(idName); }
     void setMapsecDisplayName(const QString &idName, const QString &displayName);
diff --git a/src/core/validator.cpp b/src/core/validator.cpp
index 6f7a72a7..2b0fcf0b 100644
--- a/src/core/validator.cpp
+++ b/src/core/validator.cpp
@@ -35,7 +35,8 @@ void PrefixValidator::fixup(QString &input) const {
         input.prepend(m_prefix);
 }
 
-bool PrefixValidator::isValid(QString &input) const {
+bool PrefixValidator::isValid(const QString &input) const {
     int pos = 0;
-    return validate(input, pos) == QValidator::Acceptable;
+    QString s(input);
+    return validate(s, pos) == QValidator::Acceptable;
 }
diff --git a/src/project.cpp b/src/project.cpp
index cf779d5c..5dc4e67d 100644
--- a/src/project.cpp
+++ b/src/project.cpp
@@ -346,11 +346,8 @@ Map *Project::createNewMap(const Project::NewMapSettings &settings, const Map* t
     }
     map->setLayout(layout);
 
-    const QString location = map->header()->location();
-    if (!this->mapSectionIdNames.contains(location) && isValidNewIdentifier(location)) {
-        // Unrecognized MAPSEC name, we can automatically add a new MAPSEC for it.
-        addNewMapsec(location);
-    }
+    // Try to record the MAPSEC name in case this is a new name.
+    addNewMapsec(map->header()->location());
 
     this->mapNames.insert(mapNamePos, map->name());
     this->groupNameToMapNames[settings.group].append(map->name());
@@ -1251,6 +1248,9 @@ void Project::saveMap(Map *map, bool skipLayout) {
 
     if (!skipLayout) saveLayout(map->layout());
 
+    // Try to record the MAPSEC name in case this is a new name.
+    addNewMapsec(map->header()->location());
+
     map->setClean();
 }
 
@@ -1925,8 +1925,8 @@ bool Project::isIdentifierUnique(const QString &identifier) const {
 }
 
 // For some arbitrary string, return true if it's both a valid identifier name and not one that's already in-use.
-bool Project::isValidNewIdentifier(QString identifier) const {
-    IdentifierValidator validator;
+bool Project::isValidNewIdentifier(const QString &identifier) const {
+    static const IdentifierValidator validator;
     return validator.isValid(identifier) && isIdentifierUnique(identifier);
 }
 
@@ -2332,8 +2332,18 @@ QString Project::getMapGroupPrefix() {
     return QStringLiteral("gMapGroup_");
 }
 
-// This function assumes a valid and unique name
-void Project::addNewMapsec(const QString &idName) {
+bool Project::addNewMapsec(const QString &idName, const QString &displayName) {
+    if (this->mapSectionIdNames.contains(idName)) {
+        // Already added
+        return false;
+    }
+
+    IdentifierValidator validator(projectConfig.getIdentifier(ProjectIdentifier::define_map_section_prefix));
+    if (!validator.isValid(idName)) {
+        logWarn(QString("Cannot add new MAPSEC with invalid name '%1'").arg(idName));
+        return false;
+    }
+
     if (this->mapSectionIdNamesSaveOrder.last() == getEmptyMapsecName()) {
         // If the default map section name (MAPSEC_NONE) is last in the list we'll keep it last in the list.
         this->mapSectionIdNamesSaveOrder.insert(this->mapSectionIdNames.length() - 1, idName);
@@ -2348,6 +2358,8 @@ void Project::addNewMapsec(const QString &idName) {
 
     emit mapSectionAdded(idName);
     emit mapSectionIdNamesChanged(this->mapSectionIdNames);
+    if (!displayName.isEmpty()) setMapsecDisplayName(idName, displayName);
+    return true;
 }
 
 void Project::removeMapsec(const QString &idName) {
diff --git a/src/ui/newlocationdialog.cpp b/src/ui/newlocationdialog.cpp
index d0586d99..b21904fd 100644
--- a/src/ui/newlocationdialog.cpp
+++ b/src/ui/newlocationdialog.cpp
@@ -69,11 +69,7 @@ void NewLocationDialog::accept() {
     if (!validateIdName())
         return;
 
-    const QString idName = ui->lineEdit_IdName->text();
-    const QString displayName = ui->lineEdit_DisplayName->text();
-
-    this->project->addNewMapsec(idName);
-    this->project->setMapsecDisplayName(idName, displayName);
+    this->project->addNewMapsec(ui->lineEdit_IdName->text(), ui->lineEdit_DisplayName->text());
 
     QDialog::accept();
 }