diff --git a/pwdbased.h b/pwdbased.h
index 99d2c3f4..f755724b 100644
--- a/pwdbased.h
+++ b/pwdbased.h
@@ -6,6 +6,7 @@
 #include "cryptlib.h"
 #include "hmac.h"
 #include "hrtimer.h"
+#include "integer.h"
 
 NAMESPACE_BEGIN(CryptoPP)