diff --git a/trio.h b/trio.h
index eab1b6d..108a709 100644
--- a/trio.h
+++ b/trio.h
@@ -28,7 +28,7 @@
  * Use autoconf defines if present. Packages using trio must define
  * HAVE_CONFIG_H as a compiler option themselves.
  */
-#if defined(HAVE_CONFIG_H)
+#if defined(TRIO_HAVE_CONFIG_H)
 # include "config.h"
 #endif