diff --git a/include/osmocom/core/msgb.h b/include/osmocom/core/msgb.h
index 91b7ec7..9c3ccf0 100644
--- a/include/osmocom/core/msgb.h
+++ b/include/osmocom/core/msgb.h
@@ -498,5 +498,6 @@
 
 void *msgb_talloc_ctx_init(void *root_ctx, unsigned int pool_size);
 void msgb_set_talloc_ctx(void *ctx) OSMO_DEPRECATED("Use msgb_talloc_ctx_init() instead");
+int msgb_printf(struct msgb *msgb, const char *format, ...);
 
 /*! @} */