diff --git a/examples/formatter-biome.toml b/examples/formatter-biome.toml
index 21d9ee9f..dc47163d 100644
--- a/examples/formatter-biome.toml
+++ b/examples/formatter-biome.toml
@@ -2,5 +2,5 @@
 [formatter.biome]
 command = "biome"
 excludes = []
-includes = ["*.js", "*.ts", "*.mjs", "*.mts", "*.cjs", "*.cts", "*.jsx", "*.tsx", "*.json", "*.jsonc"]
+includes = ["*.js", "*.ts", "*.mjs", "*.mts", "*.cjs", "*.cts", "*.jsx", "*.tsx", "*.d.ts", "*.d.cts", "*.d.mts", "*.json", "*.jsonc"]
 options = ["format", "--write", "--no-errors-on-unmatched"]
diff --git a/programs/biome.nix b/programs/biome.nix
index b4b011f2..c0731142 100644
--- a/programs/biome.nix
+++ b/programs/biome.nix
@@ -18,6 +18,9 @@ let
     "*.cts"
     "*.jsx"
     "*.tsx"
+    "*.d.ts"
+    "*.d.cts"
+    "*.d.mts"
   ];
 
   ext.json = [