diff --git a/racket/syndicate/actor.rkt b/racket/syndicate/actor.rkt
index 3f4d4a2..5864a92 100644
--- a/racket/syndicate/actor.rkt
+++ b/racket/syndicate/actor.rkt
@@ -345,42 +345,67 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Queries
 
-(define-syntax-rule (query-set field-name P expr)
-  (let ()
-    (field [field-name (set)])
-    (on (asserted P) #:priority *query-priority*
-        (field-name (set-add (field-name) expr)))
-    (on (retracted P) #:priority *query-priority*
-        (field-name (set-remove (field-name) expr)))
-    field-name))
+(begin-for-syntax
+  (define-splicing-syntax-class on-add
+    (pattern (~optional (~seq #:on-add expr) #:defaults ([expr #f]))))
+  (define-splicing-syntax-class on-remove
+    (pattern (~optional (~seq #:on-remove expr) #:defaults ([expr #f]))))
 
-(define-syntax-rule (query-hash field-name P key-expr value-expr)
-  (let ()
-    (field [field-name (hash)])
-    (on (asserted P) #:priority *query-priority*
-        (let ((key key-expr))
-          (when (hash-has-key? (field-name) key)
-            (log-warning "query-hash: field ~v with pattern ~v: overwriting existing entry ~v"
-                         'field-name
-                         'P
-                         key))
-          (field-name (hash-set (field-name) key value-expr))))
-    (on (retracted P) #:priority *query-priority*
-        (field-name (hash-remove (field-name) key-expr)))
-    field-name))
+  (define (schedule-query-handler-stxs maybe-expr-stx)
+    (if maybe-expr-stx
+        #`((schedule-script! #:priority *query-handler-priority*
+                             #f
+                             (lambda () #,maybe-expr-stx)))
+        #'())))
 
-(define-syntax-rule (query-hash-set field-name P key-expr value-expr)
-  (let ()
-    (field [field-name (hash)])
-    (on (asserted P) #:priority *query-priority*
-        (field-name (hashset-add (field-name) key-expr value-expr)))
-    (on (retracted P) #:priority
-        *query-priority* (field-name (hashset-remove (field-name) key-expr value-expr)))
-    field-name))
+(define-syntax (query-set stx)
+  (syntax-parse stx
+    [(_ field-name P expr on-add:on-add on-remove:on-remove)
+     #`(let ()
+         (field [field-name (set)])
+         (on (asserted P) #:priority *query-priority*
+             #,@(schedule-query-handler-stxs (attribute on-add.expr))
+             (field-name (set-add (field-name) expr)))
+         (on (retracted P) #:priority *query-priority*
+             #,@(schedule-query-handler-stxs (attribute on-remove.expr))
+             (field-name (set-remove (field-name) expr)))
+         field-name)]))
 
-(define-syntax-rule (define/query-set id P expr) (define id (query-set id P expr)))
-(define-syntax-rule (define/query-hash id P k v) (define id (query-hash id P k v)))
-(define-syntax-rule (define/query-hash-set id P k v) (define id (query-hash-set id P k v)))
+(define-syntax (query-hash stx)
+  (syntax-parse stx
+    [(_ field-name P key-expr value-expr on-add:on-add on-remove:on-remove)
+     #`(let ()
+         (field [field-name (hash)])
+         (on (asserted P) #:priority *query-priority*
+             (let ((key key-expr))
+               (when (hash-has-key? (field-name) key)
+                 (log-warning "query-hash: field ~v with pattern ~v: overwriting existing entry ~v"
+                              'field-name
+                              'P
+                              key))
+               #,@(schedule-query-handler-stxs (attribute on-add.expr))
+               (field-name (hash-set (field-name) key value-expr))))
+         (on (retracted P) #:priority *query-priority*
+             #,@(schedule-query-handler-stxs (attribute on-remove.expr))
+             (field-name (hash-remove (field-name) key-expr)))
+         field-name)]))
+
+(define-syntax (query-hash-set stx)
+  (syntax-parse stx
+    [(_ field-name P key-expr value-expr on-add:on-add on-remove:on-remove)
+     #`(let ()
+         (field [field-name (hash)])
+         (on (asserted P) #:priority *query-priority*
+             #,@(schedule-query-handler-stxs (attribute on-add.expr))
+             (field-name (hashset-add (field-name) key-expr value-expr)))
+         (on (retracted P) #:priority *query-priority*
+             #,@(schedule-query-handler-stxs (attribute on-remove.expr))
+             (field-name (hashset-remove (field-name) key-expr value-expr)))
+         field-name)]))
+
+(define-syntax-rule (define/query-set id P x ...) (define id (query-set id P x ...)))
+(define-syntax-rule (define/query-hash id P x ...) (define id (query-hash id P x ...)))
+(define-syntax-rule (define/query-hash-set id P x ...) (define id (query-hash-set id P x ...)))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Syntax-time support
diff --git a/racket/syndicate/examples/actor/query-set.rkt b/racket/syndicate/examples/actor/query-set.rkt
index 8802b78..6ac2ed7 100644
--- a/racket/syndicate/examples/actor/query-set.rkt
+++ b/racket/syndicate/examples/actor/query-set.rkt
@@ -4,7 +4,9 @@
 
 (actor #:name 'queryer
        (forever
-        (define/query-set as-set `(item ,$a ,$b) (list a b))
+        (define/query-set as-set `(item ,$a ,$b) (list a b)
+          #:on-add (log-info "as-set adding ~v/~v" a b)
+          #:on-remove (log-info "as-set removing ~v/~v" a b))
         (define/query-hash as-hash `(item ,$a ,$b) a b)
         (define/query-hash-set as-hash-set `(item ,$a ,$b) a b)