diff --git a/vcl/source/glyphs/graphite_layout.cxx b/vcl/source/glyphs/graphite_layout.cxx
index 4edeb9a..42332e2 100644
--- a/vcl/source/glyphs/graphite_layout.cxx
+++ b/vcl/source/glyphs/graphite_layout.cxx
@@ -849,6 +849,7 @@ void GraphiteLayout::expandOrCondense(ImplLayoutArgs &rArgs)
                     nOffset = static_cast<int>(fExtraPerCluster * nCluster);
                     int nCharIndex = mvGlyph2Char[i];
                     assert(nCharIndex > -1);
+                    if (nCharIndex < mnMinCharPos) continue;
                     mvCharDxs[nCharIndex-mnMinCharPos] += nOffset;
                     // adjust char dxs for rest of characters in cluster
                     while (++nCharIndex - mnMinCharPos < static_cast<int>(mvChar2BaseGlyph.size()))