diff --git a/aegisub/src/audio_player_oss.h b/aegisub/src/audio_player_oss.h
index 585d531da..d94c1bbe7 100644
--- a/aegisub/src/audio_player_oss.h
+++ b/aegisub/src/audio_player_oss.h
@@ -37,6 +37,8 @@
 #ifdef WITH_OSS
 #ifndef AGI_PRE
 #include <sys/ioctl.h>
+
+#include <wx/thread.h>
 #endif
 
 #include <fcntl.h>