diff --git a/io/io_canread.c b/io/io_canread.c
index b7261b8..6050723 100644
--- a/io/io_canread.c
+++ b/io/io_canread.c
@@ -32,7 +32,7 @@ int64 io_canread() {
       alt_firstread=r;
       debug_printf(("io_canread: enqueue %ld in alt read queue (next is %ld)\n",alt_firstread,e->next_read));
 #endif
-      if (io_waitmode!=SIGIO)
+      if (io_waitmode!=_SIGIO)
 	e->canread=0;
       return r;
     }
diff --git a/io/io_canwrite.c b/io/io_canwrite.c
index 9875e6e..153eb19 100644
--- a/io/io_canwrite.c
+++ b/io/io_canwrite.c
@@ -32,7 +32,7 @@ int64 io_canwrite() {
       alt_firstwrite=r;
       debug_printf(("io_canwrite: enqueue %ld in alt write queue (next is %ld)\n",alt_firstwrite,e->next_write));
 #endif
-      if (io_waitmode!=SIGIO)
+      if (io_waitmode!=_SIGIO)
 	e->canwrite=0;
       return r;
     }