diff --git a/bin/Makefile b/bin/Makefile
index 51fa3b3..261a6bd 100644
--- a/bin/Makefile
+++ b/bin/Makefile
@@ -38,18 +38,6 @@ ifdef LDATA_DEF
 CFLAGS += -DLDATA_DEF=$(LDATA_DEF)
 endif
 
-# OS Stuff.
-
-# Linux Stuff.
-ifeq ($(OS),LINUX)
-CFLAGS += -D_POSIX_SOURCE
-endif
-
-# FreeBSD stuff.
-ifeq ($(OS),FREEBSD)
-	CFLAGS += -D_POSIX_SOURCE -D__BSD_VISIBLE
-endif
-
 # Debug stuff.
 ifdef DEBUG
 CFLAGS += -W -Wall -Wextra -Wunused -Wshadow -Wpointer-arith -Wmissing-prototypes \
@@ -67,11 +55,6 @@ ifeq ($(OS), LINUX)
 LDFLAGS += -rdynamic
 endif # Linux.
 
-# FreeBSD stuff.
-ifeq ($(OS), FREEBSD)
-	LDFLAGS += -rdynamic
-endif
-
 else # DEBUG
 CFLAGS += -O2 -funroll-loops -pipe -std=c99
 endif
diff --git a/src/lcompat.h b/src/lcompat.h
new file mode 100644
index 0000000..132fd2d
--- /dev/null
+++ b/src/lcompat.h
@@ -0,0 +1,11 @@
+#pragma once
+
+/* System specific. */
+#define HAS_LINUX     (defined(linux) || defined(__linux) || defined(__linux__))
+#define HAS_FREEBSD   (defined(__FreeBSD__))
+#define HAS_HAS_WIN32 (defined(__WIN32))
+
+/* Standard specific. */
+#define HAS_POSIX     HAS_UNIX /* (defined(_POSIX_VERSION) && (_POSIX_VERSION >= 200112L)) */
+#define HAS_UNIX      (defined(__unix__) || defined(__unix))
+
diff --git a/src/lephisto.c b/src/lephisto.c
index 6d53c2c..da763c1 100644
--- a/src/lephisto.c
+++ b/src/lephisto.c
@@ -11,14 +11,16 @@
 
 #include <SDL/SDL.h>
 
+#include "lcompat.h"
+
 /* Global. */
 #include <string.h>
-#if defined(LINUX) && !defined(DEBUGGING)
+#if HAS_LINUX && defined(DEBUG) /* DEBUGGING isn't defined yet. */
 #include <signal.h>
 #include <execinfo.h>
 #include <stdlib.h>
 #include <unistd.h>
-#endif /* defined(LINUX) && !defined(DEBUGGING) */
+#endif /* HAS_LINUX && defined(DEBUG) */
 
 /* Local. */
 #include "lephisto.h"
@@ -606,7 +608,7 @@ static void print_SDLversion(void) {
     WARN("SDL is older than compiled version.");
 }
 
-#if defined(LINUX) && !defined(DEBUGGING)
+#if HAS_LINUX && defined(DEBUGGING)
 /**
  * @brief Get the string related to the signal code.
  *    @param sig Signal to which code belongs.
@@ -667,13 +669,13 @@ static void debug_sigHandler(int sig, siginfo_t* info, void* unused) {
 
   exit(1);
 }
-#endif /* defined(LINUX) && !defined(DEBUG) */
+#endif /* HAS_LINUX && defined(DEBUGGING) */
 
 /**
  * @brief Set up the SignalHandler for Linux.
  */
 static void debug_sigInit(void) {
-#if defined(LINUX) && !defined(DEBUGGING)
+#if HAS_LINUX && defined(DEBUGGING)
   struct sigaction sa, so;
 
   /* Set up handler. */
@@ -692,6 +694,6 @@ static void debug_sigInit(void) {
   sigaction(SIGABRT, &sa, &so);
   if(so.sa_handler == SIG_IGN)
     DEBUG("Unable to get set up SIGABRT signal handler.");
-#endif /* #if defined(LINUX) && !defined(DEBUGGING) */
+#endif /* #if HAS_LINUX && defined(DEBUGGING) */
 }
 
diff --git a/src/lfile.c b/src/lfile.c
index e3237b1..7783b65 100644
--- a/src/lfile.c
+++ b/src/lfile.c
@@ -6,17 +6,19 @@
  * @todo Add support for windows and mac OS.
  */
 
+#include "lcompat.h"
+
 #include <stdio.h>
 #include <string.h>
 #include <stdarg.h>
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <dirent.h>
 #include <errno.h>
-#endif
+#endif /* HAS_POSIX */
 
 #include "lephisto.h"
 #include "log.h"
@@ -33,10 +35,10 @@ char* lfile_basePath(void) {
   char* home;
 
   if(lephisto_base[0] == '\0') {
-#if defined(LINUX) || defined(FREEBSD)
+#if HAS_UNIX
     home = getenv("HOME");
     snprintf(lephisto_base, PATH_MAX, "%s/.lephisto/", home);
-#else
+#else /* HAS_UNIX */
     FILE* f;
 
     /* Try to open the file, C89 compliant, but not as precise as stat. */
@@ -69,7 +71,7 @@ int lfile_dirMakeExist(const char* path, ...) {
     va_end(ap);
   }
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   struct stat buf;
 
   stat(file, &buf);
@@ -78,9 +80,9 @@ int lfile_dirMakeExist(const char* path, ...) {
       WARN("Dir '%s' does not exist and unable to create", file);
       return -1;
     }
-#else
-#error "Needs implentation."
-#endif
+#else /* HAS_POSIX */
+#error "Feature needs implementation on this Operating System for Lephisto to work."
+#endif /* HAS_POSIX */
 
   return 0;
 }
@@ -101,14 +103,21 @@ int lfile_fileExists(const char* path, ...) {
     va_end(ap);
   }
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   struct stat buf;
 
   if(stat(file, &buf)==0) /* Stat worked, file must exist. */
     return 1;
-#else
-#error "Needs implementation."
-#endif
+#else /* HAS_POSIX */
+  FILE* f;
+
+  /* Try to open the file, C89 compliant, but not as precise as stat. */
+  f = fopen(file, 'r');
+  if(f != NULL) {
+    fclose(f);
+    return 1;
+  }
+#endif /* HAS_POSIX */
   return 0;
 }
 
@@ -134,7 +143,7 @@ char** lfile_readDir(int* lfiles, const char* path, ...) {
     va_end(ap);
   }
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   int i, j, k, n;
   DIR* d;
   struct dirent *dir;
@@ -216,9 +225,9 @@ char** lfile_readDir(int* lfiles, const char* path, ...) {
   free(tfiles);
   free(tt);
 
-#else
-#error "Needs implementation."
-#endif
+#else /* HAS_POSIX */
+#error "Feature needs implementation on this Operating System for Lephito to work."
+#endif /* HAS_POSIX
 
   /* What if we find nothing? */
   if((*lfiles) == 0) {
diff --git a/src/pack.c b/src/pack.c
index f8b4005..ad2185c 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -1,5 +1,10 @@
 #include <stdio.h>
-#include <sys/stat.h> /* S_IRUSR */
+#include <fcntl.h>      /* creat() etc. */
+#include <stdint.h>     /* uint32_t */
+#if HAS_POSIX
+#include <sys/types.h>  /* ssize_t */
+#include <sys/stat.h>   /* S_IRUSR */
+#endif /* HAS_POSIX */
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
@@ -36,11 +41,11 @@
  * @brief Abstracts around packfiles.
  */
 struct Packfile_s {
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   int fd; /**< File descriptor. */
 #else
   FILE* fp; /**< For non-posix. */
-#endif
+#endif /* HAS_POSIX */
   uint32_t pos;   /**< Cursor position. */
   uint32_t start; /**< File start. */
   uint32_t end;   /**< File end. */
@@ -52,11 +57,11 @@ struct Packfile_s {
  * @brief Allows much faster creation of packfiles.
  */
 struct Packcache_s {
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   int fd; /**< File descriptor. */
 #else
   FILE* fp; /* For non-posix. */
-#endif
+#endif /* HAS_POSIX */
 
   char** index;     /**< Cached index for faster lookups. */
   uint32_t* start;  /**< Cached index starts. */
@@ -64,7 +69,7 @@ struct Packcache_s {
 };
 
 /* Helper defines. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
 #define READ(f, b, n) if(read((f)->fd, (b), (n)) != (n)) { \
   ERR("Fewer bytes read then expected"); \
   return NULL; }
@@ -72,7 +77,7 @@ struct Packcache_s {
 #define READ(f, b, n) if(fread((b), 1, (n),(f)->fp) != (n)) { \
   ERR("Fewer bytes read then expected"); \
   return NULL; }
-#endif
+#endif /* HAS_POSIX */
 
 #undef DEBUG /* This will be spammy. */
 #define DEBUG(str, args...) do{;} while(0) /**< Hack to disable debugging. */
@@ -112,13 +117,13 @@ Packcache_t* pack_openCache(const char* packfile) {
   }
 
   /* Open file. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   cache->fd = open(packfile, O_RDONLY);
   if(cache->fd == -1) {
 #else
   cache->fp = fopen(packfile, "rb");
   if(cache->fp == NULL) {
-#endif
+#endif /* HAS_POSIX */
     ERR("Error opening %s: %s", packfile, strerror(errno));
     return NULL;
   } 
@@ -157,11 +162,11 @@ void pack_closeCache(Packcache_t* cache) {
   uint32_t i;
 
   /* Close file. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   close(cache->fd);
 #else
   fclose(cache->fp);
-#endif
+#endif /* HAS_POSIX */
 
   /* Free memory. */
   if(cache->nindex > 0) {
@@ -188,7 +193,7 @@ Packfile_t* pack_openFromCache(Packcache_t* cache, const char* filename) {
   for(i = 0; i < cache->nindex; i++) {
     if(strcmp(cache->index[i], filename)==0) {
       /* Copy file. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
       file->fd = dup(cache->fd);
 #else
       file->fp = cache->fp;
@@ -200,12 +205,12 @@ Packfile_t* pack_openFromCache(Packcache_t* cache, const char* filename) {
 
       /* Seek. */
       if(file->start) { /* Go to the beginning of the file. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
         if((uint32_t)lseek(file->fd, file->start, SEEK_SET) != file->start) {
 #else
         fseek(file->fp, file->start, SEEK_SET);
         if(errno) {
-#endif
+#endif /* HAS_POSIX */
           ERR("Failure to seek to file start: %s", strerror(errno));
           return NULL;
         }
@@ -231,7 +236,7 @@ Packfile_t* pack_openFromCache(Packcache_t* cache, const char* filename) {
  *    @return The size of the file.
  */
 static off_t getfilesize(const char* filename) {
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   struct stat file;
 
   if(!stat(filename, &file))
@@ -250,7 +255,7 @@ static off_t getfilesize(const char* filename) {
   fclose(fp);
 
   return size;
-#endif
+#endif /* HAS_POSIX */
 }
 
 /**
@@ -266,7 +271,7 @@ int pack_check(const char* filename) {
 
   buf = malloc(sizeof(magic));
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   int fd = open(filename, O_RDONLY);
   if(fd == -1) {
     ERR("Error opening %s: %s", filename, strerror(errno));
@@ -296,13 +301,13 @@ int pack_check(const char* filename) {
 
   ret = (memcmp(buf, &magic, sizeof(magic))==0) ? 0 : 1;
   fclose(file);
-#endif
+#endif /* HAS_POSIX */
 
   free(buf);
   return ret;
 }
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
 #define WRITE(b,n) if(write(outfd, b, n)==-1) { \
   ERR("Error writing to file: %s", strerror(errno)); \
   free(buf); return -1; } /**< Macro to help check for errors.
@@ -310,7 +315,7 @@ int pack_check(const char* filename) {
 #define WRITE(b,n) if(fwrite(b, 1, n, outf)==0) { \
   ERR("Error writing to file: %s", strerror(errno)); \
   free(buf); return -1; } /**< Macro to help check for errors. */
-#endif
+#endif /* HAS_POSIX */
 
 /**
  * @brief Packages files into a packfile.
@@ -321,12 +326,12 @@ int pack_check(const char* filename) {
  */
 int pack_files(const char* outfile, const char** infiles, const uint32_t nfiles) {
   void* buf;
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   struct stat file;
   int outfd, infd;
 #else
   FILE* outf, *inf;
-#endif
+#endif /* HAS_POSIX */
   uint32_t i;
   int namesize;
   uint32_t indexsize, pointer;
@@ -335,11 +340,11 @@ int pack_files(const char* outfile, const char** infiles, const uint32_t nfiles)
 
   for(namesize = 0, i = 0; i < nfiles; i++) {
     /* Make sure file exists before writing. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
     if(stat(infiles[i], &file)) {
 #else
     if(getfilesize(infiles[i]) == 0) {
-#endif
+#endif /* HAS_POSIX */
       ERR("File %s does not exist", infiles[i]);
       return -1;
     }
@@ -357,13 +362,13 @@ int pack_files(const char* outfile, const char** infiles, const uint32_t nfiles)
   DEBUG("Index size is %d", indexsize);
 
   /* Create the output file. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   outfd = creat(outfile, PERMS);
   if(outfd == -1) {
 #else
   outf = fopen(outfile, "wb");
   if(outf == NULL) {
-#endif
+#endif /* HAS_POSIX */
     ERR("Unable to open %s for writing", outfile);
     return -1;
   }
@@ -395,32 +400,32 @@ int pack_files(const char* outfile, const char** infiles, const uint32_t nfiles)
     WRITE(&bytes, 4); /* filesize. */
     DEBUG("About to write '%s' of %d bytes", infiles[i], bytes);
     md5_init(&md5);
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
     infd = open(infiles[i], O_RDONLY);
     while((bytes = read(infd, buf, BLOCKSIZE))) {
 #else
     inf = fopen(infiles[i], "rb");
     while((bytes = fread(buf, 1, BLOCKSIZE, inf))) {
-#endif
+#endif /* HAS_POSIX */
       WRITE(buf, bytes); /* Data. */
       md5_append(&md5, buf, bytes);
     }
     md5_finish(&md5, md5val);
     WRITE(md5val, 16);
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
     close(infd);
 #else
     fclose(inf);
-#endif
+#endif /* HAS_POSIX */
     DEBUG("Wrote file '%s'", infiles[i]);
   }
   free(md5val);
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   close(outfd);
 #else
   fclose(outf);
-#endif
+#endif /* HAS_POSIX */
   free(buf);
 
   DEBUG("Packfile success\n\t%d files\n\t%d bytes",
@@ -445,13 +450,13 @@ Packfile_t* pack_open(const char* packfile, const char* filename) {
   file = malloc(sizeof(Packfile_t));
   memset(file, 0, sizeof(Packfile_t));
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   file->fd = open(packfile, O_RDONLY);
   if(file->fd == -1) {
 #else
   file->fp = fopen(packfile, "rb");
   if(file->fp == NULL) {
-#endif
+#endif /* HAS_POSIX */
     ERR("Error opening %s: %s", filename, strerror(errno));
     return NULL;
   }
@@ -476,21 +481,21 @@ Packfile_t* pack_open(const char* packfile, const char* filename) {
       DEBUG("'%s' found at %d", filename, file->start);
       break;
     }
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
     lseek(file->fd, 4, SEEK_CUR); /* Ignore the file location. */
 #else
     fseek(file->fp, 4, SEEK_CUR);
-#endif
+#endif /* HAS_POSIX */
   }
 
   if(file->start) {
     /* Go to the beginning of the file. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
     if((uint32_t)lseek(file->fd, file->start, SEEK_SET) != file->start) {
 #else
     fseek(file->fp, file->start, SEEK_SET);
     if(errno) {
-#endif
+#endif /* HAS_POSIX */
       ERR("Failure to seek to file start: %s", strerror(errno));
       return NULL;
     }
@@ -521,11 +526,11 @@ ssize_t pack_read(Packfile_t* file, void* buf, size_t count) {
     count = file->end - file->pos; /* Can't go past the end! */
   if(count == 0) return 0;
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   if((bytes = read(file->fd, buf, count)) == -1) {
 #else
   if((bytes = fread(buf, 1, count, file->fp)) == -1) {
-#endif
+#endif /* HAS_POSIX */
     ERR("Error while reading file: %s", strerror(errno));
     return -1;
   }
@@ -549,7 +554,7 @@ off_t pack_seek(Packfile_t* file, off_t offset, int whence) {
   DEBUG("Attempting to seek offset: %d, whence: %d", offset, whence);
   off_t ret;
   switch(whence) {
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   case SEEK_SET:
     if((file->start + offset) > file->end) return -1;
     ret = lseek(file->fd, file->start + offset, SEEK_SET);
@@ -581,7 +586,7 @@ off_t pack_seek(Packfile_t* file, off_t offset, int whence) {
     ret = flseek(file->fd, file->end - offset - 1, SEEK_SET);
     if(ret != (file->end - offset)) return -1;
     break;
-#endif
+#endif /* HAS_POSIX */
   default:
     ERR("Whence is not one of SEEK_SET, SEEK_CUR or SEEK_END");
     return -1;
@@ -633,11 +638,11 @@ static void* pack_readfilePack(Packfile_t* file,
   md5_init(&md5);
   md5_append(&md5, buf, bytes);
   md5_finish(&md5, md5val);
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   if((bytes = read(file->fd, md5fd, 16)) == -1)
 #else
   if((bytes = fread(md5fd, 1, 16, file->fp)) == -1)
-#endif
+#endif /* HAS_POSIX */
     WARN("Failure to read MD5, continuing anyway..");
   else if(memcmp(md5val, md5fd, 16))
     WARN("MD5 gives different value, possible memory corruption, continuing..");
@@ -702,13 +707,13 @@ char** pack_listfiles(const char* packfile, uint32_t* nfiles) {
 
   *nfiles = 0;
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   file.fd = open(packfile, O_RDONLY);
   if(file.fd == -1) {
 #else
   file.fp = fopen(packfile, "rb");
   if(file.fp == NULL) {
-#endif
+#endif /* HAS_POSIX */
     ERR("opening %s: %s", packfile, strerror(errno));
     return NULL;
   }
@@ -731,11 +736,11 @@ char** pack_listfiles(const char* packfile, uint32_t* nfiles) {
   }
   free(buf);
 
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   close(file.fd);
 #else
   fclose(file.fp);
-#endif
+#endif /* HAS_POSIX */
 
   return filenames;
 }
@@ -772,14 +777,14 @@ int pack_close(Packfile_t* file) {
   int i;
 
   /* Close files. */
-#ifdef _POSIX_SOURCE
+#if HAS_POSIX
   i = close(file->fd);
 #else
   if(file->flags & PACKFILE_FROMCACHE)
     i = 0;
   else
     i = fclose(file->fp);
-#endif
+#endif /* HAS_POSIX */
 
   /* Free memory. */
   free(file);
diff --git a/src/pack.h b/src/pack.h
index 768b118..581dbf5 100644
--- a/src/pack.h
+++ b/src/pack.h
@@ -1,10 +1,12 @@
 #pragma once
+
+#include "lcompat.h"
+
 #include <fcntl.h>
-#ifndef _POSIX_SOURCE /* No posix. */
-#include <stdio.h>
-#endif
 #include <stdint.h>
+#if HAS_POSIX
 #include <sys/types.h>
+#endif /* HAS_POSIX */
 
 struct Packfile_s;
 typedef struct Packfile_s Packfile_t;
diff --git a/src/physics.c b/src/physics.c
index e0598f5..75f8b88 100644
--- a/src/physics.c
+++ b/src/physics.c
@@ -100,7 +100,7 @@ double vect_dot(Vec2* a, Vec2* b) {
  * SOLID!
  * ================
  */
-#if defined(FREEBSD)
+#if HAS_FREEBSD
 /**
  * @brief Update the solids position using a euler integration.
  *
@@ -150,7 +150,7 @@ static void simple_update(Solid* obj, const double dt) {
   vect_cset(&obj->vel, vx, vy);
   vect_cset(&obj->pos, px, py);
 }
-#endif /* defined(FREEBSD) */
+#endif /* HAS_FREEBSD */
 
 /**
  * @brief Runge-Kutta method of updating a solid based on it's
@@ -175,7 +175,7 @@ static void simple_update(Solid* obj, const double dt) {
  * a tiny staight line.
  */
 
-#if !defined(FREEBSD)
+#if !HAS_FREEBSD
 #define RK4_MIN_H 0.01 /* Minimal pass we want. */
 static void rk4_update(Solid* obj, const double dt) {
   int i, N;                       /* For iteration and pass calculation. */
@@ -230,7 +230,7 @@ static void rk4_update(Solid* obj, const double dt) {
   }
   vect_cset(&obj->pos, px, py);
 }
-#endif /* !defined(FREEBSD) */
+#endif /* !HAS_FREEBSD */
 
 /* Initialize a new solid. */
 void solid_init(Solid* dest, const double mass, const double dir,
@@ -260,11 +260,11 @@ void solid_init(Solid* dest, const double mass, const double dir,
  * FreeBSD seems to have a bug with optimizations in rk4_update causing it to
  * eventually become NaN.
  */
-#if defined(FREEBSD)
+#if HAS_FREEBSD
   dest->update = simple_update;
 #else
   dest->update = rk4_update;
-#endif
+#endif /* HAS_FREEBSD */
 }
 
 /* Create a new solid. */
diff --git a/src/rng.c b/src/rng.c
index 46f50db..3439742 100644
--- a/src/rng.c
+++ b/src/rng.c
@@ -6,15 +6,17 @@
  * Random numbers are currently generated using the mersenne twister.
  */
 
+#include "lcompat.h"
+
 #include <stdint.h>
 #include <math.h>
 #include <unistd.h>
 #include <time.h>
 #include <errno.h>
-#if defined _POSIX_SOURCE
+#if HAS_POSIX
 #include <sys/time.h>
 #include <fcntl.h>
-#endif
+#endif /* HAS_POSIX */
 #include <SDL.h>
 
 #include "lephisto.h"
@@ -40,7 +42,7 @@ void rng_init(void) {
   int need_init;
 
   need_init = 1; /* Initialize by default. */
-#ifdef LINUX
+#if HAS_LINUX
   int fd;
   fd = open("/dev/urandom", O_RDONLY); /* /dev/urandom is better then time seed. */
   if(fd != -1) {
@@ -54,7 +56,7 @@ void rng_init(void) {
     i = rng_timeEntropy();
 #else
   i = rng_timeEntropy();
-#endif
+#endif /* HAS_LINUX */
   if(need_init)
     mt_initArray(i);
   for(i = 0; i < 10; i++)
@@ -71,16 +73,16 @@ void rng_init(void) {
 static uint32_t rng_timeEntropy(void) {
   int i;
   
-#if defined(_POSIX_SOURCE)
+#if HAS_POSIX
   struct timeval tv;
   gettimeofday(&tv, NULL);
   i = tv.tv_sec * 1000000 + tv.tv_usec;
-#elif defined(WIN32)
+#elif HAS_WIN32
   struct _timeb tb;
   _ftime(&tb);
   i = tb.time * 1000 + tb.millitm;
 #else
-#error "Needs Implmentation."
+#error "Feature needs implementation on this Operating System for Lephisto to work."
 #endif
   return i;
 }