diff --git a/flake.nix b/flake.nix
index c3702d6..17f0e5f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -20,8 +20,9 @@
             src = ./.;
             cargoLock.lockFile = ./Cargo.lock;
             buildInputs = builtins.attrValues {
-              inherit (final) installShellFiles mkvtoolnix-cli;
+              inherit (final) installShellFiles;
             };
+            env.mkvmerge = "${final.mkvtoolnix-cli}/bin/mkvmerge";
 
             postInstall = ''
               installShellCompletion --cmd subtitle-merge \
diff --git a/src/main.rs b/src/main.rs
index 31dd22f..af63d18 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -111,7 +111,7 @@ fn convert_single(
         find_files(source.parent().unwrap(), OsStr::new("ttf"))?.collect::<io::Result<_>>()?
     };
 
-    let mut command = Command::new("mkvmerge");
+    let mut command = Command::new(option_env!("mkvmerge").unwrap_or("mkvmerge"));
     command.arg("--output").args([
         output.into_os_string(),
         source.into_os_string(),