diff --git a/auth_algo.cpp b/auth_algo.cpp
index d2acebf..b71636b 100644
--- a/auth_algo.cpp
+++ b/auth_algo.cpp
@@ -37,6 +37,7 @@
         std::cerr << "Generate Session Integrity Key failed\n";
         output.resize(0);
     }
+    output.resize(integrityCheckValueLength);
 
     return output;
 }
diff --git a/auth_algo.hpp b/auth_algo.hpp
index cf5ccfe..2c3b0da 100644
--- a/auth_algo.hpp
+++ b/auth_algo.hpp
@@ -137,6 +137,8 @@
 class AlgoSHA1 : public Interface
 {
     public:
+        static constexpr size_t integrityCheckValueLength = 12;
+
         explicit AlgoSHA1(integrity::Algorithms intAlgo,
                           crypt::Algorithms cryptAlgo) :
                 Interface(intAlgo, cryptAlgo) {}