diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 17d5bb6d03a..df742a5c84c 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -15496,7 +15496,7 @@ in modules // {
       ${python.executable} setup.py test
     '';
 
-    installFlags = optional (versionAtLeast protobuf.version "2.6.0") "--cpp_implementation";
+    installFlags = optional (versionAtLeast protobuf.version "2.6.0") "--install-option='--cpp_implementation'";
 
     doCheck = true;