diff --git a/pkgs/linux-packages/rt5640/package.nix b/pkgs/linux-packages/rt5640/package.nix
index f3ddd47af..e46215e9e 100644
--- a/pkgs/linux-packages/rt5640/package.nix
+++ b/pkgs/linux-packages/rt5640/package.nix
@@ -1,6 +1,8 @@
 # C code is taken from megi's kernel tree.
 # this is a patched version of mainline driver.
-# notably, it resolves some errors like "rt5640 1-001c: ASoC: error at snd_soc_dai_set_sysclk on rt5640-aif1: -22".
+# notably, it resolves some errors like:
+# - "rt5640 1-001c: ASoC: error at snd_soc_dai_set_sysclk on rt5640-aif1: -22" (older linux, i think pre 6.13?)
+# - "rt5640: 1-001c: ASoC error (-22): at snd_soc_dai_set_sysclk() on rt5640-aif1" (linux 6.15.6+)
 #
 # the driver source lives at sound/soc/codecs/rt5640.c; it's renamed to sound-soc-rt5640 during build
 {
@@ -21,7 +23,8 @@ stdenv.mkDerivation {
 
   makeFlags = [
     # "KERNELRELEASE=${kernel.modDirVersion}"
-    "KERNEL_DIR=${kernel.dev}/lib/modules/${kernel.modDirVersion}/build"
+    # "KERNEL_DIR=${kernel.dev}/lib/modules/${kernel.modDirVersion}/build"
+    "KERNEL_DIR=$(buildRoot)"
     "INSTALL_MOD_PATH=$(out)/lib/modules/${kernel.modDirVersion}/kernel"
     # from <repo:nixos/nixpkgs:pkgs/os-specific/linux/kernel/manual-config.nix>
     "O=$(buildRoot)"
@@ -33,6 +36,14 @@ stdenv.mkDerivation {
     "CROSS_COMPILE=${stdenv.cc.targetPrefix}"
   ];
 
+  preConfigure = ''
+    # starting with linux 6.13.0 it wants to write to `KERNEL_DIR`, so we copy that here to make it writable
+    cp -R ${kernel.dev}/lib/modules/${kernel.modDirVersion}/build .
+    export buildRoot=$(pwd)/build
+
+    chmod u+w -R build
+  '';
+
   # the modules shipped in-tree are .xz, so if i want to replace those i need to also xz this module:
   postInstall = ''
     find $out -name '*.ko' -exec xz {} \;
diff --git a/pkgs/linux-packages/rt5640/snd-soc-rt5640.c b/pkgs/linux-packages/rt5640/snd-soc-rt5640.c
index b4fa38cce..d46123818 100644
--- a/pkgs/linux-packages/rt5640/snd-soc-rt5640.c
+++ b/pkgs/linux-packages/rt5640/snd-soc-rt5640.c
@@ -1804,10 +1804,10 @@ static int rt5640_set_dai_fmt(struct snd_soc_dai *dai, unsigned int fmt)
 	int dai_sel;
 
 	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
-	case SND_SOC_DAIFMT_CBM_CFM:
+	case SND_SOC_DAIFMT_CBP_CFP:
 		rt5640->master[dai->id] = 1;
 		break;
-	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBC_CFC:
 		reg_val |= RT5640_I2S_MS_S;
 		rt5640->master[dai->id] = 0;
 		break;
@@ -2999,19 +2999,19 @@ MODULE_DEVICE_TABLE(i2c, rt5640_i2c_id);
 static const struct of_device_id rt5640_of_match[] = {
 	{ .compatible = "realtek,rt5639", },
 	{ .compatible = "realtek,rt5640", },
-	{},
+	{ }
 };
 MODULE_DEVICE_TABLE(of, rt5640_of_match);
 #endif
 
 #ifdef CONFIG_ACPI
 static const struct acpi_device_id rt5640_acpi_match[] = {
-	{ "INT33CA", 0 },
-	{ "10EC3276", 0 },
-	{ "10EC5640", 0 },
-	{ "10EC5642", 0 },
-	{ "INTCCFFD", 0 },
-	{ },
+	{ "10EC3276" },
+	{ "10EC5640" },
+	{ "10EC5642" },
+	{ "INT33CA" },
+	{ "INTCCFFD" },
+	{ }
 };
 MODULE_DEVICE_TABLE(acpi, rt5640_acpi_match);
 #endif