diff --git a/pkg/urbit/compat/mingw/compat.c b/pkg/urbit/compat/mingw/compat.c
index 1fe0c97254..3ab9029b67 100644
--- a/pkg/urbit/compat/mingw/compat.c
+++ b/pkg/urbit/compat/mingw/compat.c
@@ -1,7 +1,13 @@
 #include "c/portable.h"
+#include <fcntl.h>
 #include <sys/utime.h>
 #include <windows.h>
 
+// set default CRT file mode to binary
+// note that mingw binmode.o does nothing
+#undef _fmode
+int _fmode = _O_BINARY;
+
 // from https://github.com/git/git/blob/master/compat/mingw.c
 // -----------------------------------------------------------------------
 
diff --git a/pkg/urbit/include/c/portable.h b/pkg/urbit/include/c/portable.h
index 3700a8065a..5c675a926d 100644
--- a/pkg/urbit/include/c/portable.h
+++ b/pkg/urbit/include/c/portable.h
@@ -92,10 +92,6 @@
       #error "port: headers"
 #   endif
 
-#   ifndef O_BINARY
-#     define O_BINARY 0
-#   endif
-
 #   ifndef __has_feature
 #     define __has_feature(x) 0
 #   endif
diff --git a/pkg/urbit/noun/events.c b/pkg/urbit/noun/events.c
index 0085df8ed7..224eb86d9c 100644
--- a/pkg/urbit/noun/events.c
+++ b/pkg/urbit/noun/events.c
@@ -170,7 +170,7 @@ u3e_fault(void* adr_v, c3_i ser_i)
 static c3_o
 _ce_image_open(u3e_image* img_u)
 {
-  c3_i mod_i = O_RDWR | O_BINARY | O_CREAT;
+  c3_i mod_i = O_RDWR | O_CREAT;
   c3_c ful_c[8193];
 
   snprintf(ful_c, 8192, "%s", u3P.dir_c);
@@ -274,13 +274,13 @@ _ce_patch_create(u3_ce_patch* pat_u)
   mkdir(ful_c, 0700);
 
   snprintf(ful_c, 8192, "%s/.urb/chk/control.bin", u3P.dir_c);
-  if ( -1 == (pat_u->ctl_i = open(ful_c, O_RDWR | O_BINARY | O_CREAT | O_EXCL, 0600)) ) {
+  if ( -1 == (pat_u->ctl_i = open(ful_c, O_RDWR | O_CREAT | O_EXCL, 0600)) ) {
     fprintf(stderr, "loom: patch open control.bin: %s\r\n", strerror(errno));
     c3_assert(0);
   }
 
   snprintf(ful_c, 8192, "%s/.urb/chk/memory.bin", u3P.dir_c);
-  if ( -1 == (pat_u->mem_i = open(ful_c, O_RDWR | O_BINARY | O_CREAT | O_EXCL, 0600)) ) {
+  if ( -1 == (pat_u->mem_i = open(ful_c, O_RDWR | O_CREAT | O_EXCL, 0600)) ) {
     fprintf(stderr, "loom: patch open memory.bin: %s\r\n", strerror(errno));
     c3_assert(0);
   }
@@ -376,12 +376,12 @@ _ce_patch_open(void)
   mkdir(ful_c, 0700);
 
   snprintf(ful_c, 8192, "%s/.urb/chk/control.bin", u3P.dir_c);
-  if ( -1 == (ctl_i = open(ful_c, O_RDWR | O_BINARY)) ) {
+  if ( -1 == (ctl_i = open(ful_c, O_RDWR)) ) {
     return 0;
   }
 
   snprintf(ful_c, 8192, "%s/.urb/chk/memory.bin", u3P.dir_c);
-  if ( -1 == (mem_i = open(ful_c, O_RDWR | O_BINARY)) ) {
+  if ( -1 == (mem_i = open(ful_c, O_RDWR)) ) {
     close(ctl_i);
 
     _ce_patch_delete();
diff --git a/pkg/urbit/noun/manage.c b/pkg/urbit/noun/manage.c
index 9c7abdcbce..5fd1c82aea 100644
--- a/pkg/urbit/noun/manage.c
+++ b/pkg/urbit/noun/manage.c
@@ -411,7 +411,7 @@ u3_noun
 u3m_file(c3_c* pas_c)
 {
   struct stat buf_b;
-  c3_i        fid_i = open(pas_c, O_RDONLY | O_BINARY, 0644);
+  c3_i        fid_i = open(pas_c, O_RDONLY, 0644);
   c3_w        fln_w, red_w;
   c3_y*       pad_y;
 
diff --git a/pkg/urbit/noun/trace.c b/pkg/urbit/noun/trace.c
index 2b53ae9388..1ee8168c70 100644
--- a/pkg/urbit/noun/trace.c
+++ b/pkg/urbit/noun/trace.c
@@ -288,7 +288,7 @@ u3t_trace_open(c3_c* dir_c)
   c3_c lif_c[2056];
   snprintf(lif_c, 2056, "%s/%d.json", fil_c, u3_Host.tra_u.fun_w);
 
-  u3_Host.tra_u.fil_u = fopen(lif_c, "wb");
+  u3_Host.tra_u.fil_u = fopen(lif_c, "w");
   u3_Host.tra_u.nid_w = (int)getpid();
 
   fprintf(u3_Host.tra_u.fil_u, "[ ");
diff --git a/pkg/urbit/noun/urth.c b/pkg/urbit/noun/urth.c
index 8fc0b33145..c92a7d3dad 100644
--- a/pkg/urbit/noun/urth.c
+++ b/pkg/urbit/noun/urth.c
@@ -549,7 +549,7 @@ _cu_rock_save(c3_c* dir_c, c3_d eve_d, c3_d len_d, c3_y* byt_y)
       return c3n;
     }
 
-    if ( -1 == (fid_i = open(nam_c, O_RDWR | O_BINARY | O_CREAT | O_TRUNC, 0644)) ) {
+    if ( -1 == (fid_i = open(nam_c, O_RDWR | O_CREAT | O_TRUNC, 0644)) ) {
       fprintf(stderr, "rock: open failed (%s, %" PRIu64 "): %s\r\n",
                       dir_c, eve_d, strerror(errno));
       c3_free(nam_c);
@@ -688,7 +688,7 @@ u3u_mmap_read(c3_c* cap_c, c3_c* pat_c, c3_d* out_d, c3_y** out_y)
 
   //  open file
   //
-  if ( -1 == (fid_i = open(pat_c, O_RDONLY | O_BINARY, 0644)) ) {
+  if ( -1 == (fid_i = open(pat_c, O_RDONLY, 0644)) ) {
     fprintf(stderr, "%s: open failed (%s): %s\r\n",
                     cap_c, pat_c, strerror(errno));
     return c3n;
@@ -741,7 +741,7 @@ u3u_mmap(c3_c* cap_c, c3_c* pat_c, c3_d len_d, c3_y** out_y)
 
   //  open file
   //
-  if ( -1 == (fid_i = open(pat_c, O_RDWR | O_BINARY | O_CREAT | O_TRUNC, 0644)) ) {
+  if ( -1 == (fid_i = open(pat_c, O_RDWR | O_CREAT | O_TRUNC, 0644)) ) {
     fprintf(stderr, "%s: open failed (%s): %s\r\n",
                     cap_c, pat_c, strerror(errno));
     return c3n;
diff --git a/pkg/urbit/vere/dawn.c b/pkg/urbit/vere/dawn.c
index a7663235b3..349999102a 100644
--- a/pkg/urbit/vere/dawn.c
+++ b/pkg/urbit/vere/dawn.c
@@ -520,7 +520,7 @@ _dawn_come(u3_noun stars)
         c3_c  pat_c[64];
         snprintf(pat_c, 64, "%s.key", who_c + 1);
 
-        FILE* fil_u = fopen(pat_c, "wb");
+        FILE* fil_u = fopen(pat_c, "w");
         fprintf(fil_u, "%s\n", key_c);
         fclose(fil_u);
       }
diff --git a/pkg/urbit/vere/io/http.c b/pkg/urbit/vere/io/http.c
index e9a7c7d9e4..4e8e2e6d43 100644
--- a/pkg/urbit/vere/io/http.c
+++ b/pkg/urbit/vere/io/http.c
@@ -1600,7 +1600,7 @@ _http_write_ports_file(u3_httd* htd_u, c3_c *pax_c)
   c3_c* paf_c = c3_malloc(len_w);
   snprintf(paf_c, len_w, "%s/%s", pax_c, nam_c);
 
-  c3_i por_i = open(paf_c, O_WRONLY | O_BINARY | O_CREAT | O_TRUNC, 0666);
+  c3_i por_i = open(paf_c, O_WRONLY | O_CREAT | O_TRUNC, 0666);
   c3_free(paf_c);
 
   u3_http* htp_u = htd_u->htp_u;
diff --git a/pkg/urbit/vere/io/unix.c b/pkg/urbit/vere/io/unix.c
index 2885686c4a..a485d5115b 100644
--- a/pkg/urbit/vere/io/unix.c
+++ b/pkg/urbit/vere/io/unix.c
@@ -225,7 +225,7 @@ _unix_mkdir(c3_c* pax_c)
 static c3_w
 _unix_write_file_hard(c3_c* pax_c, u3_noun mim)
 {
-  c3_i  fid_i = open(pax_c, O_WRONLY | O_BINARY | O_CREAT | O_TRUNC, 0666);
+  c3_i  fid_i = open(pax_c, O_WRONLY | O_CREAT | O_TRUNC, 0666);
   c3_w  len_w, rit_w, siz_w, mug_w = 0;
   c3_y* dat_y;
 
@@ -268,7 +268,7 @@ static void
 _unix_write_file_soft(u3_ufil* fil_u, u3_noun mim)
 {
   struct stat buf_u;
-  c3_i  fid_i = open(fil_u->pax_c, O_RDONLY | O_BINARY, 0644);
+  c3_i  fid_i = open(fil_u->pax_c, O_RDONLY, 0644);
   c3_ws len_ws, red_ws;
   c3_w  old_w;
   c3_y* old_y;
@@ -692,7 +692,7 @@ _unix_update_file(u3_unix* unx_u, u3_ufil* fil_u)
   fil_u->dry = c3n;
 
   struct stat buf_u;
-  c3_i  fid_i = open(fil_u->pax_c, O_RDONLY | O_BINARY, 0644);
+  c3_i  fid_i = open(fil_u->pax_c, O_RDONLY, 0644);
   c3_ws len_ws, red_ws;
   c3_y* dat_y;
 
@@ -795,7 +795,7 @@ _unix_update_dir(u3_unix* unx_u, u3_udir* dir_u)
         }
         else {
           struct stat buf_u;
-          c3_i  fid_i = open(nod_u->pax_c, O_RDONLY | O_BINARY, 0644);
+          c3_i  fid_i = open(nod_u->pax_c, O_RDONLY, 0644);
 
           if ( (fid_i < 0) || (fstat(fid_i, &buf_u) < 0) ) {
             if ( ENOENT != errno ) {
@@ -965,7 +965,7 @@ static u3_noun
 _unix_initial_update_file(c3_c* pax_c, c3_c* bas_c)
 {
   struct stat buf_u;
-  c3_i  fid_i = open(pax_c, O_RDONLY | O_BINARY, 0644);
+  c3_i  fid_i = open(pax_c, O_RDONLY, 0644);
   c3_ws len_ws, red_ws;
   c3_y* dat_y;
 
@@ -1281,7 +1281,7 @@ u3_unix_acquire(c3_c* pax_c)
   c3_w pid_w;
   FILE* loq_u;
 
-  if ( NULL != (loq_u = fopen(paf_c, "rb")) ) {
+  if ( NULL != (loq_u = fopen(paf_c, "r")) ) {
     if ( 1 != fscanf(loq_u, "%" SCNu32, &pid_w) ) {
       u3l_log("lockfile %s is corrupt!\n", paf_c);
       kill(getpid(), SIGTERM);
@@ -1319,7 +1319,7 @@ u3_unix_acquire(c3_c* pax_c)
     unlink(paf_c);
   }
 
-  if ( NULL == (loq_u = fopen(paf_c, "wb")) ) {
+  if ( NULL == (loq_u = fopen(paf_c, "w")) ) {
     u3l_log("unix: unable to open %s\n", paf_c);
     c3_assert(0);
   }
diff --git a/pkg/urbit/vere/king.c b/pkg/urbit/vere/king.c
index bf6adea698..bc65fc7e85 100644
--- a/pkg/urbit/vere/king.c
+++ b/pkg/urbit/vere/king.c
@@ -916,7 +916,7 @@ u3_king_grab(void* vod_p)
     c3_c man_c[2048];
     snprintf(man_c, 2048, "%s/%s-daemon.txt", nam_c, wen_c);
 
-    fil_u = fopen(man_c, "wb");
+    fil_u = fopen(man_c, "w");
     fprintf(fil_u, "%s\r\n", wen_c);
 
     c3_free(wen_c);
diff --git a/pkg/urbit/vere/walk.c b/pkg/urbit/vere/walk.c
index 4d03f12bdd..5c113cbac7 100644
--- a/pkg/urbit/vere/walk.c
+++ b/pkg/urbit/vere/walk.c
@@ -32,7 +32,7 @@ u3_noun
 u3_walk_safe(c3_c* pas_c)
 {
   struct stat buf_b;
-  c3_i        fid_i = open(pas_c, O_RDONLY | O_BINARY, 0644);
+  c3_i        fid_i = open(pas_c, O_RDONLY, 0644);
   c3_w        fln_w, red_w;
   c3_y*       pad_y;
 
@@ -64,7 +64,7 @@ u3_noun
 u3_walk_load(c3_c* pas_c)
 {
   struct stat buf_b;
-  c3_i        fid_i = open(pas_c, O_RDONLY | O_BINARY, 0644);
+  c3_i        fid_i = open(pas_c, O_RDONLY, 0644);
   c3_w        fln_w, red_w;
   c3_y*       pad_y;
 
@@ -130,7 +130,7 @@ _walk_mkdirp(c3_c* bas_c, u3_noun pax)
 void
 u3_walk_save(c3_c* pas_c, u3_noun tim, u3_atom pad, c3_c* bas_c, u3_noun pax)
 {
-  c3_i  fid_i = open(pas_c, O_WRONLY | O_BINARY | O_CREAT | O_TRUNC, 0666);
+  c3_i  fid_i = open(pas_c, O_WRONLY | O_CREAT | O_TRUNC, 0666);
   c3_w  fln_w, rit_w;
   c3_y* pad_y;
 
diff --git a/pkg/urbit/worker/main.c b/pkg/urbit/worker/main.c
index c1cff83ea0..8c4001d8d8 100644
--- a/pkg/urbit/worker/main.c
+++ b/pkg/urbit/worker/main.c
@@ -130,7 +130,7 @@ _cw_serf_stdio(c3_i* inn_i, c3_i* out_i)
   //  we replace [FD 0] (stdin) with a fd pointing to /dev/null
   //  we replace [FD 1] (stdout) with a dup of [FD 2] (stderr)
   //
-  c3_i nul_i = open("/dev/null", O_RDWR | O_BINARY, 0);
+  c3_i nul_i = open("/dev/null", O_RDWR, 0);
 
   *inn_i = dup(0);
   *out_i = dup(1);
diff --git a/pkg/urbit/worker/serf.c b/pkg/urbit/worker/serf.c
index 2376d8e48a..8ed603b90f 100644
--- a/pkg/urbit/worker/serf.c
+++ b/pkg/urbit/worker/serf.c
@@ -210,7 +210,7 @@ _serf_grab(u3_serf* sef_u)
       c3_c man_c[2054];
       snprintf(man_c, 2053, "%s/%s-serf.txt", nam_c, wen_c);
 
-      fil_u = fopen(man_c, "wb");
+      fil_u = fopen(man_c, "w");
       fprintf(fil_u, "%s\r\n", wen_c);
 
       c3_free(wen_c);
@@ -809,7 +809,7 @@ _serf_writ_live_exit(u3_serf* sef_u, c3_w cod_w)
       c3_c man_c[2054];
       snprintf(man_c, 2053, "%s/%s.txt", nam_c, wen_c);
 
-      fil_u = fopen(man_c, "wb");
+      fil_u = fopen(man_c, "w");
 
       c3_free(wen_c);
       u3z(wen);