diff --git a/rules/misc.lua b/rules/misc.lua
index 4bc8b3b90..095334cf9 100644
--- a/rules/misc.lua
+++ b/rules/misc.lua
@@ -195,7 +195,7 @@ rspamd_config.HEADER_FORGED_MDN = {
     if header_mdn and not header_rp  then return true end
     if header_rp  and not header_mdn then return false end
 
-    if header_mdn['addr'] ~= header_rp['addr'] then
+    if header_mdn and header_mdn['addr'] ~= header_rp['addr'] then
       return true
     end