diff --git a/core/templates/hashfuncs.h b/core/templates/hashfuncs.h
index 9bfc144653..41938b61aa 100644
--- a/core/templates/hashfuncs.h
+++ b/core/templates/hashfuncs.h
@@ -55,6 +55,10 @@
 #include "core/templates/rid.h"
 #include "core/typedefs.h"
 
+#ifdef _MSC_VER
+#include <intrin.h> // Needed for `__umulh` below.
+#endif
+
 /**
  * Hashing functions
  */