diff --git a/vcl/source/fontsubset/sft.cxx b/vcl/source/fontsubset/sft.cxx
index f101670d9ab5..f59b571eb329 100644
--- a/vcl/source/fontsubset/sft.cxx
+++ b/vcl/source/fontsubset/sft.cxx
@@ -348,7 +348,13 @@ static int GetSimpleTTOutline(AbstractTrueTypeFont const *ttf, sal_uInt32 glyphI
     if (glyphID >= ttf->glyphCount())
         return 0;
 
-    const sal_uInt8* ptr = table + ttf->glyphOffset(glyphID);
+    sal_uInt32 nGlyphOffset = ttf->glyphOffset(glyphID);
+    if (nGlyphOffset > nTableSize)
+        return 0;
+
+    const sal_uInt8* ptr = table + nGlyphOffset;
+    const sal_uInt32 nMaxGlyphSize = nTableSize - nGlyphOffset;
+
     const sal_Int16 numberOfContours = GetInt16(ptr, GLYF_numberOfContours_offset);
     if( numberOfContours <= 0 )             /*- glyph is not simple */
         return 0;
@@ -363,7 +369,7 @@ static int GetSimpleTTOutline(AbstractTrueTypeFont const *ttf, sal_uInt32 glyphI
 
     /* determine the last point and be extra safe about it. But probably this code is not needed */
     sal_uInt16 lastPoint=0;
-    const sal_Int32 nMaxContours = (nTableSize - 10)/2;
+    const sal_Int32 nMaxContours = (nMaxGlyphSize - 10)/2;
     if (numberOfContours > nMaxContours)
         return 0;
     for (i=0; i<numberOfContours; i++)