diff --git a/BUILD.md b/BUILD.md
index 837e7df6be..1bc12be99c 100644
--- a/BUILD.md
+++ b/BUILD.md
@@ -46,7 +46,7 @@ If you use Linux the setup would be much easier, simply run these commands:
 
 ```bash
 sudo apt-get install -y git cmake make g++
-sudo apt-get install -y qt5-default libqt5svg5-dev
+sudo apt-get install -y qt5-default libqt5svg5-dev libcrypto++-dev
 ```
 
 > NOTE: We highly recommend to use **Ubuntu 20.04 (or above)** whenever possible.
diff --git a/zenovis/xinxinoptix/OptiXStuff.h b/zenovis/xinxinoptix/OptiXStuff.h
index 1644843984..7583c5c820 100644
--- a/zenovis/xinxinoptix/OptiXStuff.h
+++ b/zenovis/xinxinoptix/OptiXStuff.h
@@ -849,8 +849,8 @@ inline void calc_sky_cdf_map(cuTexture* tex, int nx, int ny, int nc, std::functi
 }
 
 static std::string calculateMD5(const std::vector<char>& input) {
-    CryptoPP::byte digest[CryptoPP::Weak::MD5::DIGESTSIZE];
-    CryptoPP::Weak::MD5().CalculateDigest(digest, (const CryptoPP::byte*)input.data(), input.size());
+    unsigned char digest[CryptoPP::Weak::MD5::DIGESTSIZE];
+    CryptoPP::Weak::MD5().CalculateDigest(digest, (const unsigned char*)input.data(), input.size());
     CryptoPP::HexEncoder encoder;
     std::string output;
     encoder.Attach(new CryptoPP::StringSink(output));