diff --git a/src/common/int-util.h b/src/common/int-util.h
index 7cec571ad..dcf28d38a 100644
--- a/src/common/int-util.h
+++ b/src/common/int-util.h
@@ -34,7 +34,10 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
+
+#ifndef _MSC_VER
 #include <sys/param.h>
+#endif
 
 #if defined(__ANDROID__)
 #include <byteswap.h>
@@ -206,6 +209,12 @@ static inline void memcpy_swap64(void *dst, const void *src, size_t n) {
   }
 }
 
+#if _MSC_VER
+# define LITTLE_ENDIAN	1234
+# define BIG_ENDIAN	4321
+# define BYTE_ORDER	LITTLE_ENDIAN
+#endif
+
 #if !defined(BYTE_ORDER) || !defined(LITTLE_ENDIAN) || !defined(BIG_ENDIAN)
 static_assert(false, "BYTE_ORDER is undefined. Perhaps, GNU extensions are not enabled");
 #endif
diff --git a/src/crypto/chacha.c b/src/crypto/chacha.c
index f573083be..5d3edb98d 100644
--- a/src/crypto/chacha.c
+++ b/src/crypto/chacha.c
@@ -6,7 +6,9 @@ Public domain.
 
 #include <memory.h>
 #include <stdio.h>
+#ifndef _MSC_VER
 #include <sys/param.h>
+#endif
 
 #include "chacha.h"
 #include "common/int-util.h"
diff --git a/src/crypto/oaes_lib.c b/src/crypto/oaes_lib.c
index 0afec6212..9e31ebf46 100644
--- a/src/crypto/oaes_lib.c
+++ b/src/crypto/oaes_lib.c
@@ -53,6 +53,12 @@
 #include <unistd.h>
 #endif
 
+#ifdef _MSC_VER
+#define GETPID() _getpid()
+#else
+#define GETPID() getpid()
+#endif
+
 #include "oaes_config.h"
 #include "oaes_lib.h"
 
@@ -478,7 +484,7 @@ static void oaes_get_seed( char buf[RANDSIZ + 1] )
 	sprintf( buf, "%04d%02d%02d%02d%02d%02d%03d%p%d",
 		gmTimer->tm_year + 1900, gmTimer->tm_mon + 1, gmTimer->tm_mday,
 		gmTimer->tm_hour, gmTimer->tm_min, gmTimer->tm_sec, timer.millitm,
-		_test + timer.millitm, getpid() );
+		_test + timer.millitm, GETPID() );
 	#else
 	struct timeval timer;
 	struct tm *gmTimer;
@@ -490,7 +496,7 @@ static void oaes_get_seed( char buf[RANDSIZ + 1] )
 	sprintf( buf, "%04d%02d%02d%02d%02d%02d%03d%p%d",
 		gmTimer->tm_year + 1900, gmTimer->tm_mon + 1, gmTimer->tm_mday,
 		gmTimer->tm_hour, gmTimer->tm_min, gmTimer->tm_sec, timer.tv_usec/1000,
-		_test + timer.tv_usec/1000, getpid() );
+		_test + timer.tv_usec/1000, GETPID() );
 	#endif
 		
 	if( _test )
@@ -510,7 +516,7 @@ static uint32_t oaes_get_seed(void)
 	_test = (char *) calloc( sizeof( char ), timer.millitm );
 	_ret = gmTimer->tm_year + 1900 + gmTimer->tm_mon + 1 + gmTimer->tm_mday +
 			gmTimer->tm_hour + gmTimer->tm_min + gmTimer->tm_sec + timer.millitm +
-			(uintptr_t) ( _test + timer.millitm ) + getpid();
+			(uintptr_t) ( _test + timer.millitm ) + GETPID();
 	#else
 	struct timeval timer;
 	struct tm *gmTimer;
@@ -522,7 +528,7 @@ static uint32_t oaes_get_seed(void)
 	_test = (char *) calloc( sizeof( char ), timer.tv_usec/1000 );
 	_ret = gmTimer->tm_year + 1900 + gmTimer->tm_mon + 1 + gmTimer->tm_mday +
 			gmTimer->tm_hour + gmTimer->tm_min + gmTimer->tm_sec + timer.tv_usec/1000 +
-			(uintptr_t) ( _test + timer.tv_usec/1000 ) + getpid();
+			(uintptr_t) ( _test + timer.tv_usec/1000 ) + GETPID();
 	#endif
 
 	if( _test )
diff --git a/src/crypto/tree-hash.c b/src/crypto/tree-hash.c
index eb98c31b7..812f08786 100644
--- a/src/crypto/tree-hash.c
+++ b/src/crypto/tree-hash.c
@@ -34,7 +34,9 @@
 
 #include "hash-ops.h"
 
-#if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__DragonFly__)
+#ifdef _MSC_VER
+#include <malloc.h>
+#elif !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__DragonFly__)
  #include <alloca.h>
 #else
  #include <stdlib.h>