diff --git a/pkgs/development/compilers/ghc/9.12.5.nix b/pkgs/development/compilers/ghc/9.12.5.nix
new file mode 100644
index 000000000000..0e4286f39706
--- /dev/null
+++ b/pkgs/development/compilers/ghc/9.12.5.nix
@@ -0,0 +1,5 @@
+import ./common-hadrian.nix {
+  version = "9.12.4.20260606";
+  url = "https://downloads.haskell.org/~ghc/9.12.5-rc1/ghc-9.12.4.20260606-src.tar.gz";
+  sha256 = "f78e3c6aee5c769b225f20b0ea17d03ca8df28f56e02e75d5318c60c8132753f";
+}
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index ac47671a24ad..5c814720f196 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -66,7 +66,7 @@ let
     ghc96 = sets.ghc967;
     ghc98 = sets.ghc984;
     ghc910 = sets.ghc9103;
-    ghc912 = sets.ghc9123;
+    ghc912 = sets.ghc9125;
     ghc914 = sets.ghc9141;
 
     microhs_0_15 = sets.microhs_0_15_4_0;
@@ -177,6 +177,14 @@ in
         inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
         inherit buildTargetLlvmPackages llvmPackages;
       };
+      ghc9125 = callPackage ../development/compilers/ghc/9.12.5.nix {
+        bootPkgs =
+          # No suitable bindist packaged yet
+          bb.packages.ghc9103;
+        inherit (buildPackages.python3Packages) sphinx;
+        inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
+        inherit buildTargetLlvmPackages llvmPackages;
+      };
       ghc9141 = callPackage ../development/compilers/ghc/9.14.1.nix {
         bootPkgs =
           # No suitable bindist packaged yet
@@ -284,6 +292,11 @@ in
         ghc = bh.compiler.ghc9124;
         compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-9.12.x.nix { };
       };
+      ghc9125 = callPackage ../development/haskell-modules {
+        buildHaskellPackages = bh.packages.ghc9125;
+        ghc = bh.compiler.ghc9125;
+        compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-9.12.x.nix { };
+      };
       ghc9141 = callPackage ../development/haskell-modules {
         buildHaskellPackages = bh.packages.ghc9141;
         ghc = bh.compiler.ghc9141;