diff --git a/src/qtgui/preview_plaintorich.cpp b/src/qtgui/preview_plaintorich.cpp
index 05fae66e..f3fbfbac 100644
--- a/src/qtgui/preview_plaintorich.cpp
+++ b/src/qtgui/preview_plaintorich.cpp
@@ -89,11 +89,15 @@ string PlainToRichQtPreview::startMatch(unsigned int grpidx)
     // highlighting the spurious space. The space hack only work in a
     // <pre> section. Also: having <a name=xxx></a> before the match
     // term causes the same problem (so not a possible fix).
-    string hackspace = m_spacehack? " " : "";
+    // Space does not seem to work any more (2021-04) ?
+    //   Zero Width Non Joiner works but is displayed as ? sometimes on windows.
+    //  nbsp seems to now work !
+    string hackspace = m_spacehack? "&nbsp;" : "";
     string startmarker{
-        "<a name='" + termAnchorName(m_lastanchor) + "'>" + hackspace +
-            "<span style='" + qs2utf8s(prefs.qtermstyle) + "'>"
-            };
+        "<a name='" + termAnchorName(m_lastanchor) + "'>" +
+        hackspace +
+        "<span style='" + qs2utf8s(prefs.qtermstyle) + "'>" 
+    };
     return startmarker;
 }
 
diff --git a/src/qtgui/uiprefs.ui b/src/qtgui/uiprefs.ui
index a5c4d08e..739fb322 100644
--- a/src/qtgui/uiprefs.ui
+++ b/src/qtgui/uiprefs.ui
@@ -1532,8 +1532,11 @@ May be slow for big documents.</string>
          <item>
           <widget class="QCheckBox" name="anchorTamilHackCB">
            <property name="text">
-            <string>Work around QTBUG-78923 by inserting space before anchor text</string>
+            <string>Work around Tamil QTBUG-78923 by inserting space before anchor text</string>
            </property>
+             <property name="toolTip">
+              <string>The bug causes a strange circle characters to be displayed inside highlighted Tamil words. The workaround inserts an additional space character which appears to fix the problem.</string>
+             </property>
           </widget>
          </item>
          <item>