diff --git a/sw/qa/extras/ooxmlexport/data/fdo76979.docx b/sw/qa/extras/ooxmlexport/data/fdo76979.docx
new file mode 100644
index 000000000000..f8ee9952007c
Binary files /dev/null and b/sw/qa/extras/ooxmlexport/data/fdo76979.docx differ
diff --git a/sw/qa/extras/ooxmlexport/ooxmlsdrexport.cxx b/sw/qa/extras/ooxmlexport/ooxmlsdrexport.cxx
index 417e92c5e544..535ee1a49529 100644
--- a/sw/qa/extras/ooxmlexport/ooxmlsdrexport.cxx
+++ b/sw/qa/extras/ooxmlexport/ooxmlsdrexport.cxx
@@ -1000,6 +1000,16 @@ DECLARE_OOXMLEXPORT_TEST(testFdo76249, "fdo76249.docx")
     assertXPath(pXmlDoc, "//mc:Choice/w:drawing//w:txbxContent//w:drawing//lc:lockedCanvas", 1);
 }
 
+DECLARE_OOXMLEXPORT_TEST(testFdo76979, "fdo76979.docx")
+{
+    // The problem was that black was exported as "auto" fill color, resulting in well-formed, but invalid XML.
+    xmlDocPtr pXmlDoc = parseExport("word/header2.xml");
+    if (!pXmlDoc)
+       return;
+    // This was "auto", not "FFFFFF".
+    assertXPath(pXmlDoc, "//wps:spPr/a:solidFill/a:srgbClr", "val", "FFFFFF");
+}
+
 #endif
 
 CPPUNIT_PLUGIN_IMPLEMENT();
diff --git a/sw/source/filter/ww8/docxattributeoutput.cxx b/sw/source/filter/ww8/docxattributeoutput.cxx
index caea79eded52..947cd16d1766 100644
--- a/sw/source/filter/ww8/docxattributeoutput.cxx
+++ b/sw/source/filter/ww8/docxattributeoutput.cxx
@@ -6528,7 +6528,7 @@ boost::optional<sal_Int32> lcl_getDmlAlpha(const SvxBrushItem& rBrush)
 
 void DocxAttributeOutput::FormatBackground( const SvxBrushItem& rBrush )
 {
-    OString sColor = msfilter::util::ConvertColor( rBrush.GetColor( ) );
+    OString sColor = msfilter::util::ConvertColor( rBrush.GetColor().GetRGBColor() );
     boost::optional<sal_Int32> oAlpha = lcl_getDmlAlpha(rBrush);
     if (m_rExport.SdrExporter().getTextFrameSyntax())
     {