diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 0641c7439..59ef020ce 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -7525,7 +7525,8 @@ nsTextFrame::GetCharacterRectsInRange(int32_t aInOffset,
       gfxSkipCharsIterator nextIter(iter);
       nextIter.AdvanceOriginal(1);
       if (!nextIter.IsOriginalCharSkipped() &&
-          !mTextRun->IsClusterStart(nextIter.GetSkippedOffset())) {
+          !mTextRun->IsClusterStart(nextIter.GetSkippedOffset()) &&
+          nextIter.GetOriginalOffset() < kContentEnd) {
         FindClusterEnd(mTextRun, kContentEnd, &nextIter);
       }