diff --git a/include/bcrypt.h b/include/bcrypt.h
index 9e193da5de5..c71b1e8c131 100644
--- a/include/bcrypt.h
+++ b/include/bcrypt.h
@@ -82,6 +82,13 @@ typedef struct _BCRYPT_ALGORITHM_IDENTIFIER
     ULONG  dwFlags;
 } BCRYPT_ALGORITHM_IDENTIFIER;
 
+typedef struct __BCRYPT_KEY_LENGTHS_STRUCT
+{
+    ULONG dwMinLength;
+    ULONG dwMaxLength;
+    ULONG dwIncrement;
+} BCRYPT_KEY_LENGTHS_STRUCT;
+
 typedef PVOID BCRYPT_ALG_HANDLE;
 typedef PVOID BCRYPT_KEY_HANDLE;
 typedef PVOID BCRYPT_HANDLE;