diff --git a/src/managesieve/managesieve-capabilities.c b/src/managesieve/managesieve-capabilities.c
index f402f2a7e43131c51cd09eb77ce3621f4646e676..34d9fadd7ef159765a9330cbccfcc6a7dbeadc2d 100644
--- a/src/managesieve/managesieve-capabilities.c
+++ b/src/managesieve/managesieve-capabilities.c
@@ -79,6 +79,8 @@ void managesieve_capabilities_dump(void)
 
 	svinst = sieve_init(&svenv, &sieve_callbacks,
 			    (void *) global_plugin_settings, FALSE);
+	if (svinst == NULL)
+		i_fatal("Failed to initialize Sieve");
 
 	/* Dump capabilities */