diff --git a/autotests/parttest.h b/autotests/parttest.h
--- a/autotests/parttest.h
+++ b/autotests/parttest.h
@@ -33,6 +33,7 @@
 
     void testOpenUrlArguments();
     void testAutomaticMimeType();
+    void testEmptyUrlAfterCloseUrl();
 
     void testToolbarVisibility();
 };
diff --git a/autotests/parttest.cpp b/autotests/parttest.cpp
--- a/autotests/parttest.cpp
+++ b/autotests/parttest.cpp
@@ -22,6 +22,7 @@
 #include <ksharedconfig.h>
 #include <kparts/readonlypart.h>
 #include <kparts/openurlarguments.h>
+#include <QSignalSpy>
 #include <QTest>
 #include <QWidget>
 
@@ -170,6 +171,23 @@
     delete part;
 }
 
+void PartTest::testEmptyUrlAfterCloseUrl()
+{
+    TestPart *part = new TestPart(nullptr, nullptr);
+
+    QVERIFY(part->openUrl(QUrl::fromLocalFile(QFINDTESTDATA("notepad.desktop"))));
+    QSignalSpy spy(part, &KParts::ReadOnlyPart::urlChanged);
+    QVERIFY(part->openUrl(QUrl::fromLocalFile(QFINDTESTDATA("parttest.cpp"))));
+    QVERIFY(!part->url().isEmpty());
+    QCOMPARE(spy.count(), 1);
+    spy.clear();
+    QVERIFY(part->closeUrl());
+    QVERIFY(part->url().isEmpty());
+    QCOMPARE(spy.count(), 1);
+
+    delete part;
+}
+
 #include <kparts/mainwindow.h>
 #include <ktoolbar.h>
 #include <kconfiggroup.h>
diff --git a/src/readonlypart.cpp b/src/readonlypart.cpp
--- a/src/readonlypart.cpp
+++ b/src/readonlypart.cpp
@@ -137,7 +137,10 @@
         d->m_bAutoDetectedMime = false;
     }
     OpenUrlArguments args = d->m_arguments;
-    if (!closeUrl()) {
+    d->m_closeUrlFromOpenUrl = true;
+    const bool closed = closeUrl();
+    d->m_closeUrlFromOpenUrl = false;
+    if (!closed) {
         return false;
     }
     d->m_arguments = args;
@@ -238,13 +241,18 @@
     }
 }
 
+// TODO KF6: make it non-virtual so that we can just call
+// closeUrlImpl() + setUrl(QUrl()) and get rid of m_closeUrlFromOpenUrl.
 bool ReadOnlyPart::closeUrl()
 {
     Q_D(ReadOnlyPart);
 
     abortLoad(); //just in case
 
     d->m_arguments = KParts::OpenUrlArguments();
+    if (!d->m_closeUrlFromOpenUrl) {
+        setUrl(QUrl());
+    }
 
     if (d->m_bTemp) {
         QFile::remove(d->m_file);
diff --git a/src/readonlypart_p.h b/src/readonlypart_p.h
--- a/src/readonlypart_p.h
+++ b/src/readonlypart_p.h
@@ -50,6 +50,7 @@
         m_duringSaveAs = false;
         m_bTemp = false;
         m_bAutoDetectedMime = false;
+        m_closeUrlFromOpenUrl = false;
     }
 
     ~ReadOnlyPartPrivate()
@@ -79,6 +80,8 @@
 
     // whether the mimetype in the arguments was detected by the part itself
     bool m_bAutoDetectedMime : 1;
+    // Whether we are calling closeUrl() from openUrl().
+    bool m_closeUrlFromOpenUrl;
 
     /**
      * Remote (or local) url - the one displayed to the user.