diff --git a/src/THcInterface.cxx b/src/THcInterface.cxx
index ca109ca8e59ca5e796599143ce7d316c4f953f14..a74e5fd45e8311ff260cae3373536849f192fcba 100644
--- a/src/THcInterface.cxx
+++ b/src/THcInterface.cxx
@@ -10,6 +10,7 @@ for the Hall C style parameter database.
 
 #include "TROOT.h"
 #include "THcInterface.h"
+#include "TInterpreter.h"
 #include "THcParmList.h"
 #include "THcDetectorMap.h"
 #include "THcGlobals.h"