Index: galerautils/src/gu_fdesc.cpp
--- galerautils/src/gu_fdesc.cpp.orig
+++ galerautils/src/gu_fdesc.cpp
@@ -235,6 +235,9 @@ namespace gu
 #if defined(__APPLE__)
         if (-1 == fcntl (fd_, F_SETSIZE, size_) && -1 == ftruncate (fd_, size_))
         {
+#elif defined(__OpenBSD__)
+        {
+            errno = ENOSYS;
 #else
         int const ret = posix_fallocate (fd_, start, diff);
         if (0 != ret)