diff --git a/nixos/tests/hibernate.nix b/nixos/tests/hibernate.nix
index 4f05b99a5a11..fc6857e2fd02 100644
--- a/nixos/tests/hibernate.nix
+++ b/nixos/tests/hibernate.nix
@@ -51,6 +51,7 @@ in makeTest {
         connect-timeout = 1
       '';
 
+      virtualisation.memorySize = 2048;
       virtualisation.diskSize = 8 * 1024;
       virtualisation.emptyDiskImages = [
         # Small root disk for installer
diff --git a/pkgs/build-support/vm/default.nix b/pkgs/build-support/vm/default.nix
index a0f3b5efbaeb..e403b27d9690 100644
--- a/pkgs/build-support/vm/default.nix
+++ b/pkgs/build-support/vm/default.nix
@@ -1177,6 +1177,7 @@ rec {
   # The default 9P msize value is 8 KiB, which according to QEMU is
   # insufficient and would degrade performance.
   # See: https://wiki.qemu.org/Documentation/9psetup#msize
-  # Use 500 KiB as a conservative default, see also https://github.com/NixOS/nixpkgs/pull/142577#issuecomment-953848731
-  default9PMsizeBytes = 512000;
+  # Use 128KiB which is the default in linux 5.15+
+  # https://github.com/torvalds/linux/commit/9c4d94dc9a64426d2fa0255097a3a84f6ff2eebe
+  default9PMsizeBytes = 128 * 1024;
 }