diff --git a/private/rules.rkt b/private/rules.rkt
index f17e9b2..2d52d22 100644
--- a/private/rules.rkt
+++ b/private/rules.rkt
@@ -39,7 +39,7 @@
               'pronouns "awoo:pronouns")))
 
 ;; transforms the xexpr into an xexpr that includes links to hashtags
-(define (process-hashtags xexpr instance-url hashtags)
+(define (process-hashtags! xexpr instance-url hashtags)
   (define (process+ xexpr)
     (match xexpr
       [(list tag attrs children ...)
@@ -72,7 +72,7 @@
           (define bio-md (port->string (hash-ref in "src/bio.md")))
 
           (define bio-hashtags (mutable-set))
-          (define bio-xs (map (lambda (b) (process-hashtags b instance-url bio-hashtags))
+          (define bio-xs (map (lambda (b) (process-hashtags! b instance-url bio-hashtags))
                               (parse-markdown bio-md)))
           (define bio (apply string-append (map xexpr->string bio-xs)))