diff --git a/testApp/remote/testmonitorfifo.cpp b/testApp/remote/testmonitorfifo.cpp
index eb0bac4..2aa8117 100644
--- a/testApp/remote/testmonitorfifo.cpp
+++ b/testApp/remote/testmonitorfifo.cpp
@@ -8,6 +8,7 @@
 #include <pv/pvUnitTest.h>
 #include <testMain.h>
 #include <epicsMutex.h>
+#include <epicsGuard.h>
 
 #include <pv/pvAccess.h>
 #include <pv/current_function.h>