diff --git a/source-builder/sb/options.py b/source-builder/sb/options.py
index 4ce83b7..2eddd24 100644
--- a/source-builder/sb/options.py
+++ b/source-builder/sb/options.py
@@ -260,9 +260,6 @@ class command_line:
                 raise error.general('macro file not found: %s' % (um[checked.index(False)]))
             for m in um:
                 self.defaults.load(m)
-        # Check the prefix permission
-        if not self.no_install() and not path.ispathwritable(self.defaults['_prefix']):
-            raise error.general('prefix is not writable: %s' % (path.host(self.defaults['_prefix'])))
 
     def command(self):
         return path.join(self.command_path, self.command_name)
diff --git a/source-builder/sb/setbuilder.py b/source-builder/sb/setbuilder.py
index e0e942d..701e201 100644
--- a/source-builder/sb/setbuilder.py
+++ b/source-builder/sb/setbuilder.py
@@ -367,6 +367,10 @@ def run():
         else:
             deps = None
         if not list_bset_cfg_files(opts, configs):
+            prefix = opts.defaults.expand('%{_prefix}')
+            if not opts.dry_run() and not opts.no_install() and \
+                    not path.ispathwritable(prefix):
+                raise error.general('prefix is not writable: %s' % (path.host(prefix)))
             for bset in opts.params():
                 b = buildset(bset, configs, opts)
                 b.build(deps)