diff --git a/pjrpc/client/exceptions.py b/pjrpc/client/exceptions.py
index e3dd4fa..a0ccca2 100644
--- a/pjrpc/client/exceptions.py
+++ b/pjrpc/client/exceptions.py
@@ -20,7 +20,7 @@
 ]
 
 
-@dc.dataclass(frozen=True)
+@dc.dataclass
 class JsonRpcError(exceptions.JsonRpcError):
     """
     Client JSON-RPC error.
diff --git a/pjrpc/common/exceptions.py b/pjrpc/common/exceptions.py
index 115efdd..97cccef 100644
--- a/pjrpc/common/exceptions.py
+++ b/pjrpc/common/exceptions.py
@@ -35,7 +35,7 @@ class DeserializationError(ProtocolError, ValueError):
     """
 
 
-@dc.dataclass(frozen=True)
+@dc.dataclass
 class JsonRpcError(BaseError):
     """
     `JSON-RPC <https://www.jsonrpc.org>`_ protocol error.
diff --git a/pjrpc/server/exceptions.py b/pjrpc/server/exceptions.py
index 1474c98..760a63f 100644
--- a/pjrpc/server/exceptions.py
+++ b/pjrpc/server/exceptions.py
@@ -20,7 +20,7 @@
 ]
 
 
-@dc.dataclass(frozen=True)
+@dc.dataclass
 class JsonRpcError(exceptions.JsonRpcError):
     """
     Server JSON-RPC error.