diff --git a/aegisub/src/audio_player_oss.cpp b/aegisub/src/audio_player_oss.cpp
index fb8d30364..5ef20d8e6 100644
--- a/aegisub/src/audio_player_oss.cpp
+++ b/aegisub/src/audio_player_oss.cpp
@@ -36,6 +36,10 @@
 
 #ifdef WITH_OSS
 
+#ifndef AGI_PRE
+#include <sys/param.h>
+#endif
+
 #include <libaegisub/log.h>
 
 #include "audio_player_oss.h"