diff --git a/README.md b/README.md
index 5459be2938bc74aa3747565f946ecc2e6abb1d41..21217a51a631a893bdcdb176a12513009c47f2ca 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,13 @@ repository head.hackage.ghc.haskell.org
        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
        7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
 
+-- To allow cabal to consider using alternative versions of packages that
+-- are patched in head.hackage, skip the `:override`:
+--
+-- active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org
+--
+-- See
+-- https://cabal.readthedocs.io/en/latest/cabal-project.html#cfg-field-active-repositories
 active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override
 ```