diff --git a/pkgs/development/tools/parsing/tree-sitter/grammars/grammar-sources.nix b/pkgs/development/tools/parsing/tree-sitter/grammars/grammar-sources.nix
index 7360c7a66d6b..75a74bbf40f4 100644
--- a/pkgs/development/tools/parsing/tree-sitter/grammars/grammar-sources.nix
+++ b/pkgs/development/tools/parsing/tree-sitter/grammars/grammar-sources.nix
@@ -1807,6 +1807,16 @@
     };
   };
 
+  opam = {
+    version = "0-unstable-2026-04-05";
+    url = "github:tmcgilchrist/tree-sitter-opam";
+    rev = "8869773f9cef795cc02da3b98cfafcaf9febc6b0";
+    hash = "sha256-q/BLM4d3H+dw93CbFLtynCJ1K4I4hJ9XBM4yaG2Z5Rk=";
+    meta = {
+      license = lib.licenses.mit;
+    };
+  };
+
   opencl = {
     version = "0-unstable-2023-03-30";
     url = "github:lefp/tree-sitter-opencl";