diff --git a/src/hb-subset-cff-common.hh b/src/hb-subset-cff-common.hh
index 7d9340010..549436414 100644
--- a/src/hb-subset-cff-common.hh
+++ b/src/hb-subset-cff-common.hh
@@ -59,7 +59,10 @@ struct ByteStrBuff : hb_vector_t<char, 1>
         return encode_byte ((v >> 8) + OpCode_TwoByteNegInt0) && encode_byte (v & 0xFF);
       }
     }
-    assert ((-32768 <= v) && (v <= 32767));
+    if (unlikely (v < -32768))
+      v = -32768;
+    else if (unlikely (v > 32767))
+      v = 32767;
     return encode_byte (OpCode_shortint) &&
            encode_byte ((v >> 8) & 0xFF) &&
            encode_byte (v & 0xFF);