diff --git a/src/BitStream.h b/src/BitStream.h
index 014c78c..1d03310 100644
--- a/src/BitStream.h
+++ b/src/BitStream.h
@@ -5,6 +5,8 @@
 #define BIT_STREAM_H
 
 #include <vector>
+#include <algorithm>
+#include <cstdint>
 
 class BitStream
 {
diff --git a/src/Main.cpp b/src/Main.cpp
index 776c84f..7515b0c 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -4,6 +4,7 @@
 #include <memory>
 #include <string>
 #include <stdio.h>
+#include <algorithm>
 #include "Compressor.h"
 
 const char* pInputFileError = "Error: Cannot open input file.\n";
@@ -72,7 +73,7 @@ int main(int argCount, char** args)
     }
 
     FILE* pInputFile;
-    if (fopen_s(&pInputFile, args[1], "rb"))
+    if ( (pInputFile = fopen(args[1], "rb")) == NULL )
     {
         printf(pInputFileError);
         return 0;
@@ -89,7 +90,7 @@ int main(int argCount, char** args)
     rewind(pInputFile);
 
     std::unique_ptr<uint8_t[]> spInputStream = std::make_unique<uint8_t[]>(inputFileSize);
-    size_t bytesRead = fread_s(spInputStream.get(), inputFileSize, 1, inputFileSize, pInputFile);
+    size_t bytesRead = fread(spInputStream.get(), 1, inputFileSize, pInputFile);
     fclose(pInputFile);
 
     if (bytesRead != inputFileSize)
@@ -105,7 +106,7 @@ int main(int argCount, char** args)
     }
 
     FILE* pOutputFile;
-    if (fopen_s(&pOutputFile, args[2], "wb"))
+    if ( (pOutputFile = fopen(args[2], "wb")) == NULL )
     {
         printf(pOutputFileError);
         return 0;
diff --git a/src/UniversalCodes.h b/src/UniversalCodes.h
index e40934f..c69cc41 100644
--- a/src/UniversalCodes.h
+++ b/src/UniversalCodes.h
@@ -5,6 +5,8 @@
 #define UNIVERSAL_CODES_H
 
 #include "BitStream.h"
+#include <cassert>
+#define _ASSERT assert
 
 uint32_t GetElias1Cost(uint32_t value);
 void EncodeElias1(BitStream& stream, uint32_t value);