diff --git a/docs/ftldns/configfile.md b/docs/ftldns/configfile.md
index eb23a89..c7aa4c1 100755
--- a/docs/ftldns/configfile.md
+++ b/docs/ftldns/configfile.md
@@ -97,6 +97,9 @@ How should `FTL` reply to blocked queries?<br>
 <hr/>
 #### `DEBUG_OVERTIME=false|true` {#debug_overtime data-toc-label='Debug overTime'}
   Print information about overTime memory operations, such as initializing or moving overTime slots.
+<hr/>
+#### `DEBUG_EXTBLOCKED=false|true` {#debug_extblocked data-toc-label='Debug externally blocked'}
+  Print information about why FTL decided that certain queries were recognized as being externally blocked.
 
 {!abbreviations.md!}