diff --git a/pkgs/by-name/pi/pict-rs/package.nix b/pkgs/by-name/pi/pict-rs/package.nix
index a781bae7ec5f..799970263a7b 100644
--- a/pkgs/by-name/pi/pict-rs/package.nix
+++ b/pkgs/by-name/pi/pict-rs/package.nix
@@ -25,9 +25,11 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   cargoHash = "sha256-wZRWusETLl32BJy5lza4Bvix500VkpXLUpQb5aO8yJ0=";
 
-  # needed for internal protobuf c wrapper library
-  PROTOC = "${protobuf}/bin/protoc";
-  PROTOC_INCLUDE = "${protobuf}/include";
+  env = {
+    # needed for internal protobuf c wrapper library
+    PROTOC = "${protobuf}/bin/protoc";
+    PROTOC_INCLUDE = "${protobuf}/include";
+  };
 
   nativeBuildInputs = [ makeWrapper ];