diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 86fa56739..c359367bb 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -40,6 +40,7 @@ Settings::Settings()
     useSQLiteWAL = true;
     syncBeforeRegistering = false;
     useSubstitutes = true;
+    buildUsersGroup = getuid() == 0 ? "nixbld" : "";
     useChroot = false;
     useSshSubstituter = false;
     impersonateLinux26 = false;