diff --git a/pkgs/by-name/li/lib60870/package.nix b/pkgs/by-name/li/lib60870/package.nix
index 2c9966ab1ac7..1884f873a1e1 100644
--- a/pkgs/by-name/li/lib60870/package.nix
+++ b/pkgs/by-name/li/lib60870/package.nix
@@ -20,6 +20,10 @@ stdenv.mkDerivation (finalAttrs: {
 
   sourceRoot = "${finalAttrs.src.name}/lib60870-C";
 
+  postPatch = lib.optionalString stdenv.hostPlatform.isDarwin ''
+    substituteInPlace src/CMakeLists.txt --replace-warn "-lrt" ""
+  '';
+
   separateDebugInfo = true;
 
   nativeBuildInputs = [ cmake ];