diff --git a/src/b-isr.c b/src/b-isr.c
index 52c3a6f..d839631 100644
--- a/src/b-isr.c
+++ b/src/b-isr.c
@@ -195,22 +195,16 @@ setup_catchsig (size_t count, int const set[VLA_ELEMS (count)])
 #undef MUST
 }
 
-#if defined HAVE_SIGALTSTACK && defined SIGSTKSZ
-#define ISR_STACK_SIZE  (10 * SIGSTKSZ)
-#else
-#define ISR_STACK_SIZE  0
-#endif
-
 struct isr_scratch *
 isr_init (bool *be_quiet)
 {
   struct isr_scratch *scratch = ZLLOC (1, struct isr_scratch);
 
-#if ISR_STACK_SIZE
+#if defined HAVE_SIGALTSTACK && defined SIGSTKSZ
   stack_t ss =
     {
-      .ss_sp = alloc (PLEXUS, "sigaltstack", ISR_STACK_SIZE),
-      .ss_size = ISR_STACK_SIZE,
+     .ss_sp = alloc (PLEXUS, "sigaltstack", (10 * SIGSTKSZ)),
+      .ss_size = (10 * SIGSTKSZ),
       .ss_flags = 0
     };
 
-- 
1.8.3.1