diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index 019a8698c08..0e48b2460bc 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -412,7 +412,7 @@ let
       CIFS_POSIX        = option yes;
       CIFS_FSCACHE      = yes;
       CIFS_STATS        = whenOlder "4.19" yes;
-      CIFS_WEAK_PW_HASH = yes;
+      CIFS_WEAK_PW_HASH = whenOlder "5.15" yes;
       CIFS_UPCALL       = yes;
       CIFS_ACL          = whenOlder "5.3" yes;
       CIFS_DFS_UPCALL   = yes;
diff --git a/pkgs/os-specific/linux/kernel/linux-testing.nix b/pkgs/os-specific/linux/kernel/linux-testing.nix
index 2caea08416e..0754ff335ba 100644
--- a/pkgs/os-specific/linux/kernel/linux-testing.nix
+++ b/pkgs/os-specific/linux/kernel/linux-testing.nix
@@ -3,15 +3,15 @@
 with lib;
 
 buildLinux (args // rec {
-  version = "5.13-rc6";
-  extraMeta.branch = "5.12";
+  version = "5.15-rc6";
+  extraMeta.branch = lib.versions.majorMinor version;
 
   # modDirVersion needs to be x.y.z, will always add .0
   modDirVersion = if (modDirVersionArg == null) then builtins.replaceStrings ["-"] [".0-"] version else modDirVersionArg;
 
   src = fetchurl {
     url = "https://git.kernel.org/torvalds/t/linux-${version}.tar.gz";
-    sha256 = "sha256-PunFd6tOsmrsPItp2QX4TEVxHnvvi1BMSwWio/DTlMU=";
+    sha256 = "1lp3jqwsbd97k3bx4crs8rc2wssyaf0v8x4kl4zv7g7ww2kkg2ii";
   };
 
   # Should the testing kernels ever be built on Hydra?