diff --git a/spec/compiler.sx b/spec/compiler.sx
index c05b9be..8a6d162 100644
--- a/spec/compiler.sx
+++ b/spec/compiler.sx
@@ -429,7 +429,20 @@
           (name (if (= (type-of name-expr) "symbol")
                   (symbol-name name-expr)
                   name-expr))
-          (value (nth args 1))
+          ;; Handle :effects annotation: (define name :effects [...] value)
+          ;; Skip keyword-value pairs between name and body
+          (value (let ((rest-args (rest args)))
+                   (if (and (not (empty? rest-args))
+                            (= (type-of (first rest-args)) "keyword"))
+                     ;; Skip :keyword value pairs until we hit the body
+                     (let ((skip-annotations
+                             (fn (items)
+                               (if (empty? items) nil
+                                 (if (= (type-of (first items)) "keyword")
+                                   (skip-annotations (rest (rest items)))
+                                   (first items))))))
+                       (skip-annotations rest-args))
+                     (first rest-args))))
           (name-idx (pool-add (get em "pool") name)))
       (compile-expr em value scope false)
       (emit-op em 128)  ;; OP_DEFINE