diff --git a/pkgs/development/libraries/fmt/default.nix b/pkgs/development/libraries/fmt/default.nix
index a88e41c95873..3caa55292a91 100644
--- a/pkgs/development/libraries/fmt/default.nix
+++ b/pkgs/development/libraries/fmt/default.nix
@@ -97,4 +97,9 @@ in
       })
     ];
   };
+
+  fmt_12 = generic {
+    version = "12.0.0";
+    hash = "sha256-AZDmIeU1HbadC+K0TIAGogvVnxt0oE9U6ocpawIgl6g=";
+  };
 }
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 486b519307ce..863d30a02e86 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -7254,7 +7254,12 @@ with pkgs;
   fltk = fltk13;
   fltk-minimal = fltk13-minimal;
 
-  inherit (callPackages ../development/libraries/fmt { }) fmt_9 fmt_10 fmt_11;
+  inherit (callPackages ../development/libraries/fmt { })
+    fmt_9
+    fmt_10
+    fmt_11
+    fmt_12
+    ;
 
   fmt = fmt_11;