diff --git a/src/OT/Layout/GPOS/PairPosFormat2.hh b/src/OT/Layout/GPOS/PairPosFormat2.hh
index 83b093b98..1bb0d60ae 100644
--- a/src/OT/Layout/GPOS/PairPosFormat2.hh
+++ b/src/OT/Layout/GPOS/PairPosFormat2.hh
@@ -244,7 +244,11 @@ struct PairPosFormat2_4
 
     buffer->idx = skippy_iter.idx;
     if (len2)
+    {
       buffer->idx++;
+      // https://github.com/harfbuzz/harfbuzz/issues/3824
+      buffer->unsafe_to_break (buffer->idx - 1, buffer->idx + 1);
+    }
 
     return_trace (true);
   }
diff --git a/src/OT/Layout/GPOS/PairSet.hh b/src/OT/Layout/GPOS/PairSet.hh
index aa48d933c..b1d9f83bc 100644
--- a/src/OT/Layout/GPOS/PairSet.hh
+++ b/src/OT/Layout/GPOS/PairSet.hh
@@ -128,8 +128,13 @@ struct PairSet
 
       if (applied_first || applied_second)
         buffer->unsafe_to_break (buffer->idx, pos + 1);
+
       if (len2)
-        pos++;
+      {
+	pos++;
+	// https://github.com/harfbuzz/harfbuzz/issues/3824
+	buffer->unsafe_to_break (pos - 1, pos + 1);
+      }
 
       buffer->idx = pos;
       return_trace (true);