diff --git a/sieve/sieve.y b/sieve/sieve.y
index 06742ea37e..85a486ea1a 100644
--- a/sieve/sieve.y
+++ b/sieve/sieve.y
@@ -168,7 +168,7 @@ extern void sieverestart(FILE *f);
 
 %name-prefix "sieve"
 %defines
-%destructor  { free_tree($$);     } commands command action control thenelse elsif block ftags
+%destructor  { free_tree($$);     } commands command action control thenelse elsif block ftags ikttags
 %destructor  { free_testlist($$); } testlist tests
 %destructor  { free_test($$);     } test
 %destructor  { strarray_free($$); } optstringlist stringlist strings string1