diff --git a/lib/capture/sp-capture-util-private.h b/lib/capture/sp-capture-util-private.h
new file mode 100644
index 00000000..8a4f40d5
--- /dev/null
+++ b/lib/capture/sp-capture-util-private.h
@@ -0,0 +1,102 @@
+/* sp-capture-util-private.h
+ *
+ * Copyright © 2019 Christian Hergert <chergert@redhat.com>
+ *
+ * This file is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This file is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef SP_CAPTURE_UTIL_PRIVATE_H
+#define SP_CAPTURE_UTIL_PRIVATE_H
+
+#include <glib.h>
+
+#ifdef __linux__
+# include <sys/sendfile.h>
+#endif
+#include <errno.h>
+#include <unistd.h>
+
+#ifdef __linux__
+# define _sp_sendfile sendfile
+#else
+static inline gssize
+_sp_sendfile (gint     out_fd,
+              gint     in_fd,
+              goffset *offset,
+              gsize    count)
+{
+  gssize total = 0;
+  goffset wpos = 0;
+  goffset rpos = 0;
+
+  errno = 0;
+
+  if (offset != NULL && *offset > 0)
+    wpos = rpos = *offset;
+
+  while (count > 0)
+    {
+      guint8 buf[4096*4];
+      gssize n_written = 0;
+      gssize n_read;
+      goffset off = 0;
+      gsize to_read;
+
+      /* Try to page align */
+      if ((rpos % 4096) != 0)
+        to_read = 4096 - rpos;
+      else
+        to_read = sizeof buf;
+
+      if (to_read > count)
+        to_read = count;
+
+      errno = 0;
+      n_read = pread (in_fd, buf, to_read, rpos);
+
+      if (n_read <= 0)
+        return -1;
+
+      g_assert (count >= n_read);
+
+      count -= n_read;
+      rpos += n_read;
+
+      while (wpos < rpos)
+        {
+          g_assert (off < sizeof buf);
+
+          errno = 0;
+          n_written = write (out_fd, &buf[off], rpos - wpos);
+
+          if (n_written <= 0)
+            return -1;
+
+          wpos += n_written;
+          off += n_written;
+          total += n_written;
+        }
+    }
+
+  g_assert (count == 0);
+
+  if (offset != NULL)
+    *offset = rpos;
+
+  errno = 0;
+  return total;
+}
+#endif
+
+#endif /* SP_CAPTURE_UTIL_PRIVATE_H */