diff --git a/libisofs/data_source.c b/libisofs/data_source.c
index f404250..9abb0e3 100644
--- a/libisofs/data_source.c
+++ b/libisofs/data_source.c
@@ -21,6 +21,11 @@
 #include <fcntl.h>
 #include <unistd.h>
 
+/* O_BINARY is needed for Cygwin but undefined elsewhere */
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
 /**
  * Private data for File IsoDataSource
  */
@@ -65,7 +70,7 @@ int ds_open(IsoDataSource *src)
         return ISO_FILE_ALREADY_OPENED;
     }
 
-    fd = open(data->path, O_RDONLY);
+    fd = open(data->path, O_RDONLY | O_BINARY);
     if (fd == -1) {
         return ISO_FILE_ERROR;
     }
diff --git a/libisofs/fs_local.c b/libisofs/fs_local.c
index 2cc56fe..da40f00 100644
--- a/libisofs/fs_local.c
+++ b/libisofs/fs_local.c
@@ -30,6 +30,11 @@
 #include <libgen.h>
 #include <string.h>
 
+/* O_BINARY is needed for Cygwin but undefined elsewhere */
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
 static
 int iso_file_source_new_lfs(IsoFileSource *parent, const char *name, 
                             IsoFileSource **src);
@@ -222,7 +227,7 @@ int lfs_open(IsoFileSource *src)
         data->info.dir = opendir(path);
         data->openned = data->info.dir ? 2 : 0;
     } else {
-        data->info.fd = open(path, O_RDONLY);
+        data->info.fd = open(path, O_RDONLY | O_BINARY);
         data->openned = data->info.fd != -1 ? 1 : 0;
     }
     free(path);
diff --git a/libisofs/system_area.c b/libisofs/system_area.c
index bc0d9fe..2c228b3 100644
--- a/libisofs/system_area.c
+++ b/libisofs/system_area.c
@@ -42,6 +42,11 @@
 #include <uuid/uuid.h>
 #endif
 
+/* O_BINARY is needed for Cygwin but undefined elsewhere */
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
 
 /*
  * Create a MBR for an isohybrid enabled ISOLINUX boot image.
@@ -2079,7 +2084,7 @@ void iso_random_uuid(Ecma119Image *t, uint8_t uuid[16])
        (Weakening the result by 8 bit saves a lot of pool entropy.)
     */
     if ((counter & 0xff) == 0) {
-        fd = open("/dev/urandom", O_RDONLY);
+        fd = open("/dev/urandom", O_RDONLY | O_BINARY);
         if (fd == -1)
             goto fallback;
         ret = read(fd, uuid_urandom, 16);