diff --git a/build/profiles/freenas/config.pyd b/build/profiles/freenas/config.pyd
index c19cd39..04bc4d4 100644
--- a/build/profiles/freenas/config.pyd
+++ b/build/profiles/freenas/config.pyd
@@ -95,6 +95,10 @@ kernel_modules = [
 ]
 
 # World/kernel build configuration
+make_conf_extra = [
+    "CFLAGS += -DNS_REREAD_CONF",
+]
+
 make_conf_build = {
     "WITHOUT_ATM":                  "yes",
     "WITHOUT_BLUETOOTH":            "yes",
diff --git a/build/tools/build-os.py b/build/tools/build-os.py
index bfa9f6e..3fa65b9 100755
--- a/build/tools/build-os.py
+++ b/build/tools/build-os.py
@@ -60,6 +60,8 @@ def create_make_conf_build():
     conf = open(makeconfbuild, 'w')
     for k, v in config['make_conf_build'].items():
         conf.write('{0}={1}\n'.format(k, v))
+    for param in config['make_conf_extra']:
+        conf.write(f'{param}\n')
     conf.close()
     conf = open(objdir('make-jail.conf'), 'w')
     for k, v in config['make_conf_build'].items():