diff --git a/pkgs/by-name/je/jemalloc/package.nix b/pkgs/by-name/je/jemalloc/package.nix
index 202195c152db..88e7b776b28d 100644
--- a/pkgs/by-name/je/jemalloc/package.nix
+++ b/pkgs/by-name/je/jemalloc/package.nix
@@ -13,6 +13,18 @@
   # compatibility.
   stripPrefix ? stdenv.hostPlatform.isDarwin,
   disableInitExecTls ? false,
+  # The upstream default is dependent on the builders' page size
+  # https://github.com/jemalloc/jemalloc/issues/467
+  # https://sources.debian.org/src/jemalloc/5.3.0-3/debian/rules/
+  pageSizeLog2 ?
+    if
+      (
+        stdenv.hostPlatform.isAarch64 || stdenv.hostPlatform.isLoongArch64 || stdenv.hostPlatform.isPower64
+      )
+    then
+      16
+    else
+      12,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -46,21 +58,11 @@ stdenv.mkDerivation (finalAttrs: {
   configureFlags = [
     "--with-version=${lib.versions.majorMinor finalAttrs.version}.0-0-g${finalAttrs.src.rev}"
     "--with-lg-vaddr=${with stdenv.hostPlatform; toString (if isILP32 then 32 else parsed.cpu.bits)}"
+    (lib.strings.withFeatureAs true "lg-page" (toString pageSizeLog2))
   ]
   # see the comment on stripPrefix
   ++ lib.optional stripPrefix "--with-jemalloc-prefix="
   ++ lib.optional disableInitExecTls "--disable-initial-exec-tls"
-  # The upstream default is dependent on the builders' page size
-  # https://github.com/jemalloc/jemalloc/issues/467
-  # https://sources.debian.org/src/jemalloc/5.3.0-3/debian/rules/
-  ++ [
-    (
-      if (stdenv.hostPlatform.isAarch64 || stdenv.hostPlatform.isLoongArch64) then
-        "--with-lg-page=16"
-      else
-        "--with-lg-page=12"
-    )
-  ]
   # See https://github.com/jemalloc/jemalloc/issues/1997
   # Using a value of 48 should work on both emulated and native x86_64-darwin.
   ++ lib.optional (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86_64) "--with-lg-vaddr=48";

ig

if we reject non-int values for pageSizeKiB with an assert + informative message, then supplying an unsupported number actually displays the supported options on my end (Lix)

       error: attribute '"32"' missing
       at /home/puna/Development/nixpkgs/pkgs/by-name/je/jemalloc/package.nix:76:10:
           75|         }
           76|         ."${toString pageSizeKiB}"
             |          ^
           77|     }"

       note: trace involved the following derivations:
       derivation 'jemalloc-5.3.0-unstable-2025-09-12'

       Did you mean one of 16, 4 or 64?

maybe useful, prolly overkill. thoughts?

if we reject non-int values for pageSizeKiB with an assert + informative message at the start, then supplying an unsupported number actually displays the supported options on my end (Lix)

       error: attribute '"32"' missing
       at /home/puna/Development/nixpkgs/pkgs/by-name/je/jemalloc/package.nix:76:10:
           75|         }
           76|         ."${toString pageSizeKiB}"
             |          ^
           77|     }"

       note: trace involved the following derivations:
       derivation 'jemalloc-5.3.0-unstable-2025-09-12'

       Did you mean one of 16, 4 or 64?

maybe useful, prolly overkill. thoughts?

error:
       … while evaluating list element at index 2

       … while calling the 'toString' builtin
         at /home/amaanq/projects/nix/nixpkgs/pkgs/by-name/je/jemalloc/package.nix:70:7:
           69|     "--with-lg-page=${
           70|       toString
             |       ^
           71|         {

       error: attribute '"32"' missing
       at /home/amaanq/projects/nix/nixpkgs/pkgs/by-name/je/jemalloc/package.nix:71:9:
           70|       toString
           71|         {
             |         ^
           72|           "4" = 12;
       Did you mean one of 16, 4 or 64?

oh, way to go is prolly

let
  pageSizeMap = { 
    "4" = 12; 
    "16" = 14; 
    "64" = 16; 
  };  
in
assert lib.asserts.assertOneOf "pageSizeKiB" (toString pageSizeKiB) (
  builtins.attrNames pageSizeMap
);

assert lib.asserts.assertMsg (builtins.isInt pageSizeKiB)
  "jemalloc: pageSizeKiB must be an integer (one of 4, 16, or 64), got: ${toString pageSizeKiB}";

assert lib.asserts.assertMsg (builtins.isInt pageSizeKiB)
  "jemalloc: pageSizeKiB must be an integer (one of 4, 16, or 64), got: ${toString pageSizeKiB}";

       error: pageSizeKiB must be one of [
         "16"
         "4"
         "64"
       ], but is: "bla"

let
  pageSizeMap = {
    "4" = 12;
    "16" = 14;
    "64" = 16;
  };
in
assert lib.asserts.assertMsg
  (builtins.hasAttr (toString pageSizeKiB) pageSizeMap)
  "jemalloc: pageSizeKiB must be one of 4, 16, or 64, but is: ${toString pageSizeKiB}";

let
  pageSizeMap = {
    "4" = 12;
    "16" = 14;
    "64" = 16;
  };
in
assert lib.asserts.assertMsg (builtins.hasAttr (toString pageSizeKiB) pageSizeMap)
  "jemalloc: pageSizeKiB must be one of ${lib.concatStringsSep ", " (builtins.attrNames pageSizeMap)}, but is: ${toString pageSizeKiB}";