diff --git a/scapy/volatile.py b/scapy/volatile.py
index be811419ae8059ace051aaf1c80e395c32908874..db389a3087afe6dda975eaf2d1a39ccccd26ba72 100644
--- a/scapy/volatile.py
+++ b/scapy/volatile.py
@@ -115,10 +115,18 @@ class RandByte(RandSeq):
     def __init__(self):
         RandSeq.__init__(self, 0, 2L**8-1)
 
+class RandSByte(RandSeq):
+    def __init__(self):
+        RandSeq.__init__(self, -2L**7, 2L**7-1)
+
 class RandShort(RandSeq):
     def __init__(self):
         RandSeq.__init__(self, 0, 2L**16-1)
 
+class RandSShort(RandSeq):
+    def __init__(self):
+        RandSeq.__init__(self, -2L**15, 2L**15-1)
+
 class RandInt(RandSeq):
     def __init__(self):
         RandSeq.__init__(self, 0, 2L**32-1)