diff --git a/pkgs/by-name/am/amber-lang/fix_gnused_detection.patch b/pkgs/by-name/am/amber-lang/fix_gnused_detection.patch
new file mode 100644
index 000000000000..a4d2e99ea729
--- /dev/null
+++ b/pkgs/by-name/am/amber-lang/fix_gnused_detection.patch
@@ -0,0 +1,29 @@
+From cae2ad70d6202bc97623be8c7c123ee2736a4644 Mon Sep 17 00:00:00 2001
+From: aleksana <me@aleksana.moe>
+Date: Sun, 9 Mar 2025 21:19:27 +0800
+Subject: [PATCH] replace_regex: remove bash word boundary when detecting
+ gnused
+
+Bash linked against C libraries other than GLibc may not support GNU
+extensions of POSIX Extended Regular Regex. For example,
+
+> re='\bx'; [[ 'x' =~ $re ]] && echo "1"
+
+does not output the same result on Linux/GLibc and macOS.
+---
+ src/std/text.ab | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/std/text.ab b/src/std/text.ab
+index fe071e33..82449a02 100644
+--- a/src/std/text.ab
++++ b/src/std/text.ab
+@@ -19,7 +19,7 @@ pub fun replace_regex(source: Text, search: Text, replace: Text, extended: Bool
+             // GNU sed versions 4.0 through 4.2 support extended regex syntax,
+             // but only via the "-r" option; use that if the version information
+             // contains "GNU sed".
+-            $ re='\bCopyright\b.+\bFree Software Foundation\b'; [[ \$(sed --version 2>/dev/null) =~ \$re ]] $
++            $ re='Copyright.+Free Software Foundation'; [[ \$(sed --version 2>/dev/null) =~ \$re ]] $
+             let flag = status == 0 then "-r" else "-E"
+             return $ echo "{source}" | sed "{flag}" -e "s/{search}/{replace}/g" $
+         } else {
diff --git a/pkgs/by-name/am/amber-lang/package.nix b/pkgs/by-name/am/amber-lang/package.nix
index 45b7e19cc14b..6a9ed594d886 100644
--- a/pkgs/by-name/am/amber-lang/package.nix
+++ b/pkgs/by-name/am/amber-lang/package.nix
@@ -4,7 +4,10 @@
   rustPlatform,
   bc,
   util-linux,
+  gnused,
   makeWrapper,
+  installShellFiles,
+  stdenv,
   runCommand,
   amber-lang,
   nix-update-script,
@@ -21,6 +24,11 @@ rustPlatform.buildRustPackage rec {
     hash = "sha256-N9G/2G8+vrpr1/K7XLwgW+X2oAyAaz4qvN+EbLOCU1Q=";
   };
 
+  patches = [
+    # https://github.com/amber-lang/amber/pull/686
+    ./fix_gnused_detection.patch
+  ];
+
   useFetchCargoVendor = true;
   cargoHash = "sha256-e5+L7Qgd6hyqT1Pb9X7bVtRr+xm428Z5J4hhsYNnGtU=";
 
@@ -29,7 +37,10 @@ rustPlatform.buildRustPackage rec {
       --replace-fail 'Command::new("/usr/bin/env")' 'Command::new("env")'
   '';
 
-  nativeBuildInputs = [ makeWrapper ];
+  nativeBuildInputs = [
+    makeWrapper
+    installShellFiles
+  ];
 
   nativeCheckInputs = [
     bc
@@ -43,9 +54,14 @@ rustPlatform.buildRustPackage rec {
     "--skip=tests::formatter::all_exist"
   ];
 
-  postInstall = ''
-    wrapProgram "$out/bin/amber" --prefix PATH : "${lib.makeBinPath [ bc ]}"
-  '';
+  postInstall =
+    ''
+      wrapProgram "$out/bin/amber" --prefix PATH : "${lib.makeBinPath [ bc ]}"
+    ''
+    + lib.optionalString (stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
+      installShellCompletion --cmd amber \
+        --bash <($out/bin/amber completion)
+    '';
 
   passthru = {
     updateScript = nix-update-script { };