diff --git a/autotests/CMakeLists.txt b/autotests/CMakeLists.txt
--- a/autotests/CMakeLists.txt
+++ b/autotests/CMakeLists.txt
@@ -34,6 +34,7 @@
  deletejobtest.cpp
  urlutiltest.cpp
  batchrenamejobtest.cpp
+ ksambasharetest.cpp
  NAME_PREFIX "kiocore-"
  LINK_LIBRARIES KF5::KIOCore KF5::I18n Qt5::Test Qt5::Network
 )
diff --git a/autotests/ksambasharetest.h b/autotests/ksambasharetest.h
new file mode 100644
--- /dev/null
+++ b/autotests/ksambasharetest.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2018 Kai Uwe Broulik <kde@broulik.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KSAMBASHARETEST_H
+#define KSAMBASHARETEST_H
+
+#include <QObject>
+
+class KSambaShareTest : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void initTestCase();
+    void testAcl();
+    void testAcl_data();
+    void testOwnAcl();
+};
+
+#endif // KSAMBASHARETEST_H
+
diff --git a/autotests/ksambasharetest.cpp b/autotests/ksambasharetest.cpp
new file mode 100644
--- /dev/null
+++ b/autotests/ksambasharetest.cpp
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2018 Kai Uwe Broulik <kde@broulik.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "ksambasharetest.h"
+
+#include <KSambaShare>
+#include <KSambaShareData>
+
+#include <QTest>
+
+QTEST_MAIN(KSambaShareTest)
+
+Q_DECLARE_METATYPE(KSambaShareData::UserShareError)
+
+void KSambaShareTest::initTestCase()
+{
+    qRegisterMetaType<KSambaShareData::UserShareError>();
+}
+
+void KSambaShareTest::testAcl()
+{
+    QFETCH(QString, acl);
+    QFETCH(KSambaShareData::UserShareError, result);
+
+    KSambaShareData data;
+
+    QCOMPARE(data.setAcl(acl), result);
+}
+
+void KSambaShareTest::testAcl_data()
+{
+    QTest::addColumn<QString>("acl");
+    QTest::addColumn<KSambaShareData::UserShareError>("result");
+
+    QTest::newRow("one entry") << QStringLiteral("Everyone:r") << KSambaShareData::UserShareAclOk;
+    QTest::newRow("one entry, trailing comma") << QStringLiteral("Everyone:r,") << KSambaShareData::UserShareAclOk;
+
+    QTest::newRow("one entry with hostname") << QStringLiteral("Host\\Someone:r") << KSambaShareData::UserShareAclOk;
+
+    QTest::newRow("space in hostname") << QStringLiteral("Everyone:r,Unix User\\Someone:f,") << KSambaShareData::UserShareAclOk;
+
+    QTest::newRow("garbage") << QStringLiteral("Garbage") << KSambaShareData::UserShareAclInvalid;
+}
+
+void KSambaShareTest::testOwnAcl()
+{
+    const auto shares = KSambaShare::instance()->shareNames();
+
+    for (const QString &share : shares) {
+        KSambaShareData shareData = KSambaShare::instance()->getShareByName(share);
+
+        // KSambaShare reads acl from net usershare info's "usershare_acl" field with no validation
+        QCOMPARE(shareData.setAcl(shareData.acl()), KSambaShareData::UserShareAclOk);
+    }
+}
diff --git a/src/core/ksambashare.cpp b/src/core/ksambashare.cpp
--- a/src/core/ksambashare.cpp
+++ b/src/core/ksambashare.cpp
@@ -285,7 +285,7 @@
 
 KSambaShareData::UserShareError KSambaSharePrivate::isAclValid(const QString &acl) const
 {
-    const QRegExp aclRx(QStringLiteral("(?:(?:(\\w+\\s*)\\\\|)(\\w+\\s*):([fFrRd]{1})(?:,|))*"));
+    const QRegExp aclRx(QStringLiteral("(?:(?:(\\w(\\w|\\s)*)\\\\|)(\\w+\\s*):([fFrRd]{1})(?:,|))*"));
     // TODO: check if user is a valid smb user
     return aclRx.exactMatch(acl) ? KSambaShareData::UserShareAclOk
            : KSambaShareData::UserShareAclInvalid;