diff --git a/bolt_386.go b/bolt_386.go
index 856f401..cc21894 100644
--- a/bolt_386.go
+++ b/bolt_386.go
@@ -1,4 +1,4 @@
 package bolt
 
 // maxMapSize represents the largest mmap size supported by Bolt.
-const maxMapSize = 0xFFFFFFF // 256MB
+const maxMapSize = 0x7FFFFFFF // 2GB
diff --git a/bolt_arm.go b/bolt_arm.go
index 856f401..cc21894 100644
--- a/bolt_arm.go
+++ b/bolt_arm.go
@@ -1,4 +1,4 @@
 package bolt
 
 // maxMapSize represents the largest mmap size supported by Bolt.
-const maxMapSize = 0xFFFFFFF // 256MB
+const maxMapSize = 0x7FFFFFFF // 2GB