diff --git a/src/environment.rs b/src/environment.rs
index c924fa5..8446c48 100644
--- a/src/environment.rs
+++ b/src/environment.rs
@@ -3,7 +3,8 @@ use crate::database::wrapped::WrappedTable;
 use crate::wrapper::{ByteWrapper, ZeroCopyByteWrapper};
 use anyhow::{ensure, Context};
 use libmdbx::{
-    DatabaseFlags, Environment, EnvironmentFlags, Transaction, TransactionKind, WriteMap, RO, RW,
+    DatabaseFlags, Environment, EnvironmentFlags, Geometry, Transaction, TransactionKind, WriteMap,
+    RO, RW,
 };
 use std::marker::PhantomData;
 use std::path::Path;
@@ -18,8 +19,21 @@ impl Env {
         let mut flags = EnvironmentFlags::default();
         flags.no_sub_dir = true;
 
+        // TODO make the geometry more configurable.
+        let mut geom = Geometry::default();
+        // Don't stop the database growing until it hits 64 GiB.
+        // (The default is 1 MiB which is just not enough!)
+        geom.size = Some(1024 * 1024..64 * 1024 * 1024 * 1024);
+
+        // Grow 4 MiB at a time.
+        geom.growth_step = Some(4 * 1024 * 1024);
+        // Shrink 16 MiB at a time.
+        geom.shrink_threshold = Some(16 * 1024 * 1024);
+        // (Yes these numbers represent a large database).
+
         let environment = Environment::new()
             .set_max_dbs(256)
+            .set_geometry(geom)
             .set_flags(flags)
             .open(path)?;