diff --git a/src/cryptojwt/jwk/hmac.py b/src/cryptojwt/jwk/hmac.py
index a0ffda0f..70da83f2 100644
--- a/src/cryptojwt/jwk/hmac.py
+++ b/src/cryptojwt/jwk/hmac.py
@@ -57,7 +57,7 @@ def __init__(
             self.key = b64d(bytes(self.k))
 
         if len(self.key) < 16:
-            raise UnsupportedAlgorithm("key too short")
+            raise UnsupportedAlgorithm("client_secret too short, it should be at least 16 digits")
 
     def deserialize(self):
         self.key = b64d(bytes(self.k))