Index: src/orca/Gecko.py
===================================================================
--- src/orca/Gecko.py	(revision 2079)
+++ src/orca/Gecko.py	(working copy)
@@ -3176,7 +3176,13 @@
             # is in the raw HTML source.  This should hopefully be
             # fixed at some point, but we just ignore it for now.
             #
-            if extents != (0, 0, 0, 0):
+            validExtents = True
+            for extent in extents:
+                if extent < 0:
+                    validExtents = False
+                    break
+
+            if validExtents and extents != (0, 0, 0, 0):
                 if not self.onSameLine(extents, lineExtents):
                     if not crossedLineBoundary:
                         lineExtents = extents
@@ -3253,7 +3259,13 @@
             # is in the raw HTML source.  This should hopefully be
             # fixed at some point, but we just ignore it for now.]]]
             #
-            if extents != (0, 0, 0, 0):
+            validExtents = True
+            for extent in extents:
+                if extent < 0:
+                    validExtents = False
+                    break
+
+            if validExtents and extents != (0, 0, 0, 0):
                 if not self.onSameLine(extents, lineExtents):
                     if not crossedLineBoundary:
                         lineExtents = extents
