--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -464,6 +464,7 @@
 #if defined(_POSIX_SYNCHRONIZED_IO) && \
    !defined(__sun__) && \
    !defined(__FreeBSD__) && \
+   !defined(__OpenBSD__) && \
    !defined(__APPLE__)
 	(void) fdatasync (ifd);
 #else
@@ -507,6 +508,7 @@
 #if defined(_POSIX_SYNCHRONIZED_IO) && \
    !defined(__sun__) && \
    !defined(__FreeBSD__) && \
+   !defined(__OpenBSD__) && \
    !defined(__APPLE__)
 	(void) fdatasync (ifd);
 #else
