diff --git a/src/V3InstrCount.h b/src/V3InstrCount.h
index 6d5ba0c5a..ecc9f73ca 100644
--- a/src/V3InstrCount.h
+++ b/src/V3InstrCount.h
@@ -19,6 +19,9 @@
 //
 //*************************************************************************
 
+#ifndef _V3INSTRCOUNT_H_
+#define _V3INSTRCOUNT_H_ 1
+
 #include "config_build.h"
 #include "verilatedos.h"
 
@@ -41,3 +44,5 @@ public:
     // Optional osp is stream to dump critical path to.
     static uint32_t count(AstNode* nodep, bool assertNoDups, std::ostream* osp = NULL);
 };
+
+#endif  // guard