diff --git a/Source/Core/Core/Src/IPC_HLE/WII_IPC_HLE.cpp b/Source/Core/Core/Src/IPC_HLE/WII_IPC_HLE.cpp
index 076404ce18..3b02c2e48f 100644
--- a/Source/Core/Core/Src/IPC_HLE/WII_IPC_HLE.cpp
+++ b/Source/Core/Core/Src/IPC_HLE/WII_IPC_HLE.cpp
@@ -36,6 +36,7 @@ They will also generate a true or false return for UpdateInterrupts() in WII_IPC
 #include <map>
 #include <string>
 #include <list>
+#include <mutex>
 
 #include "Common.h"
 #include "CommonPaths.h"