diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 3822fe6..a3df4a8 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -159,4 +159,7 @@ jobs:
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
         run: |
           npm pkg set name=astroceleste-engine
+          # wasm-pack copies neither the licenses nor NOTICE (Skyfield's MIT notice).
+          cp -L ../../../LICENSE-MIT ../../../LICENSE-APACHE ../../../NOTICE .
+          npm pkg set 'files[]=LICENSE-MIT' 'files[]=LICENSE-APACHE' 'files[]=NOTICE'
           npm publish --provenance --access public
diff --git a/README.md b/README.md
index 10db9a6..6345a65 100644
--- a/README.md
+++ b/README.md
@@ -108,6 +108,12 @@ Licensed under either of
 
 at your option.
 
+The astronomical reduction (ΔT, IAU 2000A nutation, IAU 2006 precession, light-time,
+deflection and aberration) is ported from [Skyfield](https://github.com/skyfielders/python-skyfield)
+by Brandon Rhodes, used under the MIT license: see
+[NOTICE](https://github.com/ffalcinelli/astroceleste-engine/blob/main/NOTICE), which is shipped in
+every package.
+
 Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion
 in this work, as defined in the Apache-2.0 license, shall be dual licensed as above, without
 any additional terms or conditions.