diff --git a/src/RageSoundReader_ThreadedBuffer.cpp b/src/RageSoundReader_ThreadedBuffer.cpp
index 14dac250a9..68c85d87bd 100644
--- a/src/RageSoundReader_ThreadedBuffer.cpp
+++ b/src/RageSoundReader_ThreadedBuffer.cpp
@@ -4,6 +4,7 @@
 #include "RageTimer.h"
 #include "Foreach.h"
 #include "RageLog.h"
+#include <unistd.h>
 
 /* Implement threaded read-ahead buffering.
  *