diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index bdc243a149ec..76eb0b465edb 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -180,7 +180,7 @@ with stdenv.lib;
   VGA_SWITCHEROO y # Hybrid graphics support
   DRM_GMA600 y
   DRM_GMA3600 y
-  ${optionalString (versionAtLeast version "4.5") ''
+  ${optionalString (versionAtLeast version "4.5" && (versionOlder version "4.9")) ''
     DRM_AMD_POWERPLAY y # necessary for amdgpu polaris support
   ''}
 
diff --git a/pkgs/os-specific/linux/kernel/linux-testing.nix b/pkgs/os-specific/linux/kernel/linux-testing.nix
index 6b13b45d1ada..1a411a258dd8 100644
--- a/pkgs/os-specific/linux/kernel/linux-testing.nix
+++ b/pkgs/os-specific/linux/kernel/linux-testing.nix
@@ -1,13 +1,13 @@
 { stdenv, fetchurl, perl, buildLinux, ... } @ args:
 
 import ./generic.nix (args // rec {
-  version = "4.8-rc6";
-  modDirVersion = "4.8.0-rc6";
-  extraMeta.branch = "4.8";
+  version = "4.9-rc1";
+  modDirVersion = "4.9.0-rc1";
+  extraMeta.branch = "4.9";
 
   src = fetchurl {
     url = "mirror://kernel/linux/kernel/v4.x/testing/linux-${version}.tar.xz";
-    sha256 = "122qn2r3q85xqcb56lgpkiv06yrd5w742fcdjk1sribqcvl1xlqr";
+    sha256 = "1s123bs20zp1zzy0i12y63n6wsr9cwaad4110rl5ir49j6z6byqf";
   };
 
   features.iwlwifi = true;