diff --git a/src/core/osmo_io.c b/src/core/osmo_io.c
index d5fd00820..0e0a468e6 100644
--- a/src/core/osmo_io.c
+++ b/src/core/osmo_io.c
@@ -619,8 +619,11 @@ struct osmo_io_fd *osmo_iofd_setup(const void *ctx, int fd, const char *name, en
 		return NULL;
 	}
 
-	if (ioops && !check_mode_callback_compat(mode, ioops))
+	if (ioops && !check_mode_callback_compat(mode, ioops)) {
+		LOGP(DLIO, LOGL_ERROR, "iofd(%s): rejecting call-backs incompatible with mode\n",
+			name ? name : "unknown");
 		return NULL;
+	}
 
 	iofd = talloc_zero(ctx, struct osmo_io_fd);
 	if (!iofd)
@@ -869,8 +872,10 @@ void osmo_iofd_set_name(struct osmo_io_fd *iofd, const char *name)
  *  \param[in] ioops osmo_io_ops structure to be set */
 int osmo_iofd_set_ioops(struct osmo_io_fd *iofd, const struct osmo_io_ops *ioops)
 {
-	if (!check_mode_callback_compat(iofd->mode, ioops))
+	if (!check_mode_callback_compat(iofd->mode, ioops)) {
+		LOGPIO(iofd, LOGL_ERROR, "rejecting call-backs incompatible with mode\n");
 		return -EINVAL;
+	}
 
 	iofd->io_ops = *ioops;