diff --git a/purism/librem/5r4/audio.nix b/purism/librem/5r4/audio.nix
new file mode 100644
index 0000000..e44e2f3
--- /dev/null
+++ b/purism/librem/5r4/audio.nix
@@ -0,0 +1,18 @@
+{ config, lib, pkgs, ... }:
+{
+  config = lib.mkIf config.hardware.librem5.audio {
+    assertions = [{
+      assertion = config.hardware.pulseaudio.enable;
+      message = "Call audio on Librem5 requires pulse audio to be enabled through `hardware.pulseaudio.enable`.";
+    }];
+    hardware.pulseaudio = {
+      enable = true;
+      # this is required to correctly configure the modem as PA source/sink
+      extraConfig = ''
+        .include ${pkgs.librem5-base}/etc/pulse/librem5.pa
+      '';
+    };
+
+    services.dbus.packages = [ pkgs.callaudiod ];
+  };
+}
diff --git a/purism/librem/5r4/default.nix b/purism/librem/5r4/default.nix
index a0a3aec..e4f864e 100644
--- a/purism/librem/5r4/default.nix
+++ b/purism/librem/5r4/default.nix
@@ -15,10 +15,25 @@ in {
       customInitrdModules = lib.mkEnableOption (lib.mdDoc "use of custom kernel modules in the initrd.");
       installUdevPackages = lib.mkEnableOption (lib.mdDoc "installation of udev packages from librem5-base.");
       lockdownFix = lib.mkEnableOption (lib.mdDoc "fix for orientation and proximity sensors not working after lockdown.");
+      audio = lib.mkOption {
+        description = lib.mdDoc ''
+          Whether to enable and configure PulseAudio for the Librem5 modem.
+
+          This is required for audio during calls to work at all.
+        '';
+        type = lib.types.bool;
+        default = true;
+        example = false;
+      };
     };
   };
 
-  imports = [ ./initrd.nix ./wifi.nix ./lockdown-fix.nix ];
+  imports = [
+    ./audio.nix
+    ./initrd.nix
+    ./wifi.nix
+    ./lockdown-fix.nix
+  ];
 
   config = {
     hardware.librem5 = {
diff --git a/purism/librem/5r4/librem5-base/default.nix b/purism/librem/5r4/librem5-base/default.nix
index 0cc1547..da9a39e 100644
--- a/purism/librem/5r4/librem5-base/default.nix
+++ b/purism/librem/5r4/librem5-base/default.nix
@@ -1,13 +1,13 @@
 { stdenv, fetchFromGitLab, shellcheck, kmod, lib }:
 stdenv.mkDerivation {
-  pname = "librem5-udev-rules";
+  pname = "librem5-base";
   version = "unstable";
   src = fetchFromGitLab {
     domain = "source.puri.sm";
     owner = "Librem5";
     repo = "librem5-base";
-    rev = "f5b51beb144f76ef3bc483b74e19867bd6364d32";
-    hash = "sha256-5k7e4o9ak0zik+XqRV6PPwkTDf3yH3NxtLkhTyCQj7U=";
+    rev = "96b0f920cde9157332b0c16ba1135ee60a3f3259";
+    hash = "sha256-nR42dk3g0/IkVFygZ7K1SZ2KoQJeDzuMOumKdOOQS5k=";
   };
 
   buildPhase = ":";
@@ -27,6 +27,11 @@ stdenv.mkDerivation {
       cp -v "$rule" "$out/lib/udev/rules.d/''${rule#*.}.rules"
     done
     popd
+
+    mkdir -p "$out/etc/pulse"
+    cp -v "default/audio/pulse/librem5.pa" "$out/etc/pulse/librem5.pa"
+    substituteInPlace "$out/etc/pulse/librem5.pa" \
+      --replace ".include /etc/pulse/default.pa" ""
   '';
 
   postFixup = ''