diff --git a/configure b/configure
index 928e71379ef..08642ebda74 100755
--- a/configure
+++ b/configure
@@ -40,7 +40,7 @@ run_erlang() {
 
 COUCHDB_USER="$(whoami 2>/dev/null || echo couchdb)"
 JS_ENGINE=${JS_ENGINE:-"spidermonkey"}
-SM_VSN=${SM_VSN:-"91"}
+SM_VSN=${SM_VSN:-"128"}
 CLOUSEAU_MTH=${CLOUSEAU_MTH:-"dist"}
 CLOUSEAU_URI=${CLOUSEAU_URI:-"https://github.com/cloudant-labs/clouseau/releases/download/%s/clouseau-%s-dist.zip"}
 CLOUSEAU_VSN=${CLOUSEAU_VSN:-"2.25.0"}
diff --git a/configure.ps1 b/configure.ps1
index c7c730c70d3..b1231540ab3 100644
--- a/configure.ps1
+++ b/configure.ps1
@@ -12,7 +12,7 @@
   -WithClouseau              build the Clouseau search module (default false)
   -SkipDeps                  do not update Erlang dependencies (default false)
   -CouchDBUser USER          set the username to run as (defaults to current user)
-  -SpiderMonkeyVersion VSN   select the version of SpiderMonkey to use (default 91)
+  -SpiderMonkeyVersion VSN   select the version of SpiderMonkey to use (default 128)
   -JSEngine ENGINE           select JS engine to use (spidermonkey or quickjs) (default spidermonkey)
   -ClouseauVersion VSN       select the version of Clouseau to use (default 2.25.0)
   -ClouseauMethod MTH        method for Clouseau to deploy: git or dist (default dist)
@@ -60,7 +60,7 @@ Param(
     [ValidateNotNullOrEmpty()]
     [string]$CouchDBUser = [Environment]::UserName, # set the username to run as (defaults to current user)
     [ValidateNotNullOrEmpty()]
-    [string]$SpiderMonkeyVersion = "91", # select the version of SpiderMonkey to use (default 91)
+    [string]$SpiderMonkeyVersion = "128", # select the version of SpiderMonkey to use (default 91)
     [ValidateNotNullOrEmpty()]
     [string]$JSEngine = "spidermonkey", # select the JS engine (spidermonkey | quickjs) to use (default spidermonkey)
     [ValidateNotNullOrEmpty()]
diff --git a/src/couch/rebar.config.script b/src/couch/rebar.config.script
index c4e0b7a7eed..0216c38c9c4 100644
--- a/src/couch/rebar.config.script
+++ b/src/couch/rebar.config.script
@@ -98,12 +98,12 @@ SMVsn = case lists:keyfind(spidermonkey_version, 1, CouchConfig) of
     {_, "128"} ->
         "128";
     undefined ->
-        "91";
+        "128";
     {_, Unsupported} ->
         io:format(standard_error, "Unsupported SpiderMonkey version: ~s~n", [Unsupported]),
         erlang:halt(1);
     false ->
-        "91"
+        "128"
 end.
 
 ConfigH = [