diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7144b6..306b6db 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 ## [Unreleased]
 
+## [0.8.1] - 2026-03-05
+
+- Upgrade to use asherah-cobhan v0.5.1
+- Fix buffer undersize from float truncation in estimate_buffer
+
 ## [0.8.0] - 2026-03-04
 
 - Upgrade to use asherah-cobhan v0.5.0
diff --git a/ext/asherah/checksums.yml b/ext/asherah/checksums.yml
index 6fe4edb..339b3aa 100644
--- a/ext/asherah/checksums.yml
+++ b/ext/asherah/checksums.yml
@@ -1,5 +1,5 @@
-version:                v0.5.0
-libasherah-arm64.so:    8271298c357808d7e6daa4ca81ded8f39c1947a55043abe3b32359e0f5840a6c
-libasherah-x64.so:      645c0da7d1330db511c6724f08154cfae3959610bd709d60eded1c1420d2fce8
-libasherah-arm64.dylib: 909097bf62207e6927a0184e41859ccf42a62afd711cdadf69b8c5672939468b
-libasherah-x64.dylib:   e53ee66b7dd16ce587d5062e9eed8835f272653b6a91b4b5c5c1efd2ca97483e
+version:                v0.5.1
+libasherah-arm64.so:    eb1cf59da6e7006ba8044fa9b4ec471f32576f7edb1169e30f059c5f8815c044
+libasherah-x64.so:      16237a58335e86c510a20a0a6e9afa6502026e9f5fd374012db8ee9130f41eed
+libasherah-arm64.dylib: 03260e6552b7eb17b7cbe0cb6c16486bc4d17a110c1dc8ab9293cc4b678a8b80
+libasherah-x64.dylib:   df7d71223bdfc23afc29a5bf72e0294b12d632b63f135e7ac4194ec8d69c3766
diff --git a/lib/asherah.rb b/lib/asherah.rb
index a80fd87..05a1fcb 100644
--- a/lib/asherah.rb
+++ b/lib/asherah.rb
@@ -124,10 +124,12 @@ def shutdown
     private
 
     def estimate_buffer(data_bytesize, partition_bytesize)
+      est_data_len = (((data_bytesize + ESTIMATED_ENCRYPTION_OVERHEAD) * BASE64_OVERHEAD).to_i + 1)
+
       ESTIMATED_ENVELOPE_OVERHEAD +
         @intermediated_key_overhead_bytesize +
         partition_bytesize +
-        ((data_bytesize + ESTIMATED_ENCRYPTION_OVERHEAD) * BASE64_OVERHEAD)
+        est_data_len
     end
   end
 end
diff --git a/lib/asherah/version.rb b/lib/asherah/version.rb
index a9c8bff..31d3464 100644
--- a/lib/asherah/version.rb
+++ b/lib/asherah/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Asherah
-  VERSION = '0.8.0'
+  VERSION = '0.8.1'
 end