diff --git a/src/Main/options.cxx b/src/Main/options.cxx
index 4c536e576..20674f2b9 100644
--- a/src/Main/options.cxx
+++ b/src/Main/options.cxx
@@ -2933,9 +2933,14 @@ string_list Options::extractOptions() const
 
 void Options::setupRoot(int argc, char **argv)
 {
-    SGPath root;
+    SGPath root(globals->get_fg_root());
     bool usingDefaultRoot = false;
 
+    // root has already been set, so skip the fg_root setting and validation.
+    if (!root.isNull()) {
+        return;
+    }
+
   if (isOptionSet("fg-root")) {
       root = SGPath::fromLocal8Bit(valueForOption("fg-root").c_str()); // easy!
       SG_LOG(SG_GENERAL, SG_INFO, "set from command-line argument: fg_root = " << root );