diff --git a/src/i_threads.c b/src/i_threads.c
index 5ef28bd117ae23ef429284ba0daef87a90f26d7c..959fc857f6b4224405513fad85900d3c86c2a6eb 100644
--- a/src/i_threads.c
+++ b/src/i_threads.c
@@ -313,6 +313,8 @@ void I_wake_all_cond(I_cond *anchor)
 	WakeAllConditionVariable(*anchor);
 }
 #else
+#include "i_threads.h"
+
 void I_spawn_thread(const char *name, I_thread_fn entry, void *userdata)
 {
 	(void)name;