diff --git a/src/html/htmltag.cpp b/src/html/htmltag.cpp
index 0b0b894f5b..0d71df7cf7 100644
--- a/src/html/htmltag.cpp
+++ b/src/html/htmltag.cpp
@@ -131,7 +131,9 @@ wxHtmlTagsCache::wxHtmlTagsCache(const wxString& source)
                         // see if it matches
                         int match_pos = 0;
                         while (pos < lng && match_pos < tag_len && src[pos] != '>' && src[pos] != '<') {
-                            if (wxToupper(src[pos]) == tagBuffer[match_pos]) {
+                            // cast to wxChar needed to suppress warning in
+                            // Unicode build
+                            if ((wxChar)wxToupper(src[pos]) == tagBuffer[match_pos]) {
                                 ++match_pos;
                             }  
                             else if (src[pos] == wxT(' ') || src[pos] == wxT('\n') ||