diff --git a/etc/NEWS b/etc/NEWS
index 442053fa12b..3d691cfac40 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2133,6 +2133,9 @@ The command 'makefile-switch-to-browser' command is now obsolete,
 together with related commands used in the "*Macros and Targets*"
 buffer.  We recommend using an alternative like 'imenu' instead.
 
+---
+*** 'jsonrpc-default-request-timeout' is now a defcustom.
+
 
 * New Modes and Packages in Emacs 30.1
 
diff --git a/lisp/jsonrpc.el b/lisp/jsonrpc.el
index 77efcf0b590..4971e13fae3 100644
--- a/lisp/jsonrpc.el
+++ b/lisp/jsonrpc.el
@@ -466,8 +466,17 @@ ignored."
 (define-obsolete-variable-alias 'jrpc-default-request-timeout
   'jsonrpc-default-request-timeout "28.1")
 
-(defconst jsonrpc-default-request-timeout 10
-  "Time in seconds before timing out a JSONRPC request.")
+(defgroup jsonrpc nil
+  "JSON-RPC customization."
+  :prefix "jsonrpc-"
+  :group 'comm)
+
+(defcustom jsonrpc-default-request-timeout 10
+  "Time in seconds before timing out a JSON-RPC request without response."
+  :version "30.1"
+  :type 'number
+  :safe 'numberp
+  :group 'jsonrpc)
 
 
 ;;; Specific to `jsonrpc-process-connection'