diff --git a/include/syscon.h b/include/syscon.h
index 6f78b53a797d6851404115eeab0c4665465c07ee..e4e7998f8d1a31b968f3ef60ffc992032eb68066 100644
--- a/include/syscon.h
+++ b/include/syscon.h
@@ -32,7 +32,7 @@ struct s_i2c_if
   uint32_t sda; 
 };
 
-struct s_i2c_if i2c_if[2];
+extern struct s_i2c_if i2c_if[2];
 
 void timer_init(uint32_t enable);
 uint32_t timer_get_tics();