diff --git a/autotests/data/file1.pdf.gz b/autotests/data/file1.pdf.gz
new file mode 100644
index 000000000..8ca6d6add
Binary files /dev/null and b/autotests/data/file1.pdf.gz differ
diff --git a/autotests/parttest.cpp b/autotests/parttest.cpp
index 5af09284d..a2d94b7db 100644
--- a/autotests/parttest.cpp
+++ b/autotests/parttest.cpp
@@ -919,6 +919,7 @@ void PartTest::testSaveAs_data()
     QTest::addColumn<bool>("canSwapBackingFile");
 
     QTest::newRow("pdf") << KDESRCDIR "data/file1.pdf" << "pdf" << true << true;
+    QTest::newRow("pdf.gz") << KDESRCDIR "data/file1.pdf.gz" << "pdf" << true << true;
     QTest::newRow("epub") << KDESRCDIR "data/contents.epub" << "epub" << false << false;
     QTest::newRow("jpg") << KDESRCDIR "data/potato.jpg" << "jpg" << false << true;
 }
diff --git a/part.cpp b/part.cpp
index d0def4df9..37e49157a 100644
--- a/part.cpp
+++ b/part.cpp
@@ -1366,7 +1366,7 @@ Document::OpenResult Part::doOpenFile( const QMimeType &mimeA, const QString &fi
                 return Document::OpenError;
         }
 
-        m_fileLastModified = QFileInfo( fileNameToOpen ).lastModified();
+        m_fileLastModified = QFileInfo( localFilePath() ).lastModified();
         return Document::OpenSuccess;
     }
 
@@ -1462,7 +1462,7 @@ Document::OpenResult Part::doOpenFile( const QMimeType &mimeA, const QString &fi
 
     if ( openResult == Document::OpenSuccess )
     {
-        m_fileLastModified = QFileInfo( fileNameToOpen ).lastModified();
+        m_fileLastModified = QFileInfo( localFilePath() ).lastModified();
     }
     return openResult;
 }