diff --git a/substrate/core/consensus/common/src/block_import.rs b/substrate/core/consensus/common/src/block_import.rs
index f4a60d435db8f131184cd98d54587c019a13a9fe..a683bc30196c17eed45de3367385f128907cd0b9 100644
--- a/substrate/core/consensus/common/src/block_import.rs
+++ b/substrate/core/consensus/common/src/block_import.rs
@@ -137,8 +137,6 @@ impl<Block: BlockT> ImportBlock<Block> {
 	}
 }
 
-
-
 /// Block import trait.
 pub trait BlockImport<B: BlockT> {
 	type Error: ::std::error::Error + Send + 'static;
diff --git a/substrate/core/consensus/common/src/lib.rs b/substrate/core/consensus/common/src/lib.rs
index 23bde0c0568beb43c82aba2001499a292bff23ff..453b6844309eb06aa53e949ed8a546f132027f7b 100644
--- a/substrate/core/consensus/common/src/lib.rs
+++ b/substrate/core/consensus/common/src/lib.rs
@@ -14,7 +14,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate Consensus Common.  If not, see <http://www.gnu.org/licenses/>.
 
-//! Tracks offline validators.
+//! Common utilities for building and using consensus engines in substrate.
+//!
+//! Much of this crate is _unstable_ and thus the API is likely to undergo
+//! change. Implementors of traits should not rely on the interfaces to remain
+//! the same.
 
 // This provides "unused" building blocks to other crates
 #![allow(dead_code)]
diff --git a/substrate/core/finality-grandpa/src/lib.rs b/substrate/core/finality-grandpa/src/lib.rs
index aacee8fe7d78a4f45f5640d7e8be5917d76e91dd..54833f28802f8153ab93017d1adbf4c6c01ce516 100644
--- a/substrate/core/finality-grandpa/src/lib.rs
+++ b/substrate/core/finality-grandpa/src/lib.rs
@@ -16,6 +16,8 @@
 
 //! Integration of the GRANDPA finality gadget into substrate.
 //!
+//! This crate is unstable and the API and usage may change.
+//!
 //! This crate provides a long-running future that produces finality notifications.
 //!
 //! # Usage