diff --git a/src/dialogs/certificateiodialog.cpp b/src/dialogs/certificateiodialog.cpp
index 8c9fcd5..079d793 100644
--- a/src/dialogs/certificateiodialog.cpp
+++ b/src/dialogs/certificateiodialog.cpp
@@ -72,7 +72,7 @@ void CertificateIoDialog::on_select_certificate_file_button_clicked()
     if(dialog.exec() != QDialog::Accepted)
         return;
 
-    this->ui->certificate_file_name->setText(dialog.selectedFiles().first());
+    this->ui->certificate_file_name->setText(dialog.selectedFiles().constFirst());
 
     this->updateUI();
 }
@@ -88,7 +88,7 @@ void CertificateIoDialog::on_select_key_file_button_clicked()
     if(dialog.exec() != QDialog::Accepted)
         return;
 
-    this->ui->key_file_name->setText(dialog.selectedFiles().first());
+    this->ui->key_file_name->setText(dialog.selectedFiles().constFirst());
 
     this->updateUI();
 }
diff --git a/src/dialogs/newidentitiydialog.cpp b/src/dialogs/newidentitiydialog.cpp
index 30e0cc6..aa2241c 100644
--- a/src/dialogs/newidentitiydialog.cpp
+++ b/src/dialogs/newidentitiydialog.cpp
@@ -19,7 +19,7 @@ NewIdentitiyDialog::NewIdentitiyDialog(QWidget *parent) :
     ui->expiration_date->setTime(QTime(12, 00));
 
     ui->group->clear();
-    for(auto group_name : kristall::identities.groups())
+    for(const auto &group_name : kristall::identities.groups())
     {
         ui->group->addItem(group_name);
     }
diff --git a/src/identitycollection.cpp b/src/identitycollection.cpp
index 45a86a7..7ec02d6 100644
--- a/src/identitycollection.cpp
+++ b/src/identitycollection.cpp
@@ -106,7 +106,7 @@ void IdentityCollection::load(QSettings &settings)
             id->identity.certificate = QSslCertificate::fromData(
                 settings.value("certificate").toByteArray(),
                 QSsl::Der
-            ).first();
+            ).constFirst();
 
             id->identity.private_key = QSslKey(
                 settings.value("private_key").toByteArray(),
diff --git a/src/main.cpp b/src/main.cpp
index c7b6259..3daeb95 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -272,7 +272,7 @@ int main(int argc, char *argv[])
 
     auto urls = cli_parser.positionalArguments();
     if(urls.size() > 0) {
-        for(auto url_str : urls) {
+        for(const auto &url_str : urls) {
             QUrl url { url_str };
             if (url.isRelative()) {
                 if (QFile::exists(url_str)) {
diff --git a/src/trustedhostcollection.cpp b/src/trustedhostcollection.cpp
index 57a45df..5171fd3 100644
--- a/src/trustedhostcollection.cpp
+++ b/src/trustedhostcollection.cpp
@@ -104,7 +104,7 @@ void TrustedHostCollection::clear()
 
 bool TrustedHostCollection::insert(const TrustedHost &host)
 {
-    for(auto const & item : items)
+    for(auto const & item : qAsConst(items))
     {
         if(item.host_name == host.host_name)
             return false;