diff --git a/Cargo.toml b/Cargo.toml
index 43d21fa..7d19433 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "lmdb"
-version = "0.3.0"
+version = "0.4.0"
 authors = ["Dan Burkert <dan@danburkert.com>"]
 license = "Apache-2.0"
 
@@ -17,7 +17,7 @@ name = "lmdb"
 
 [dependencies.lmdb-sys]
 path = "lmdb-sys"
-version = "0.3.0"
+version = "0.4.0"
 
 [dependencies]
 bitflags = "*"
diff --git a/lmdb-sys/Cargo.toml b/lmdb-sys/Cargo.toml
index f91720a..4855586 100644
--- a/lmdb-sys/Cargo.toml
+++ b/lmdb-sys/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "lmdb-sys"
-version = "0.3.0"
+version = "0.4.0"
 authors = ["Dan Burkert <dan@danburkert.com>"]
 license = "Apache-2.0"
 description = "Rust bindings for liblmdb."