diff --git a/pkgs/applications/science/misc/root/default.nix b/pkgs/applications/science/misc/root/default.nix
index 037b8dfa09c7..2ebfd4a1a87a 100644
--- a/pkgs/applications/science/misc/root/default.nix
+++ b/pkgs/applications/science/misc/root/default.nix
@@ -191,7 +191,7 @@ stdenv.mkDerivation rec {
     "-Dpythia6=OFF"
     "-Dpythia8=OFF"
     "-Drfio=OFF"
-    "-Droot7=OFF"
+    "-Droot7=ON"
     "-Dsqlite=OFF"
     "-Dssl=ON"
     "-Dtmva=ON"