diff --git a/io/io_canread.c b/io/io_canread.c
index bca6fd5..b7261b8 100644
--- a/io/io_canread.c
+++ b/io/io_canread.c
@@ -31,9 +31,9 @@ int64 io_canread() {
       e->next_read=alt_firstread;
       alt_firstread=r;
       debug_printf(("io_canread: enqueue %ld in alt read queue (next is %ld)\n",alt_firstread,e->next_read));
-#else
-      e->canread=0;
 #endif
+      if (io_waitmode!=SIGIO)
+	e->canread=0;
       return r;
     }
   }
diff --git a/io/io_canwrite.c b/io/io_canwrite.c
index 67a0926..9875e6e 100644
--- a/io/io_canwrite.c
+++ b/io/io_canwrite.c
@@ -31,9 +31,9 @@ int64 io_canwrite() {
       e->next_write=alt_firstwrite;
       alt_firstwrite=r;
       debug_printf(("io_canwrite: enqueue %ld in alt write queue (next is %ld)\n",alt_firstwrite,e->next_write));
-#else
-      e->canwrite=0;
 #endif
+      if (io_waitmode!=SIGIO)
+	e->canwrite=0;
       return r;
     }
   }