diff --git a/pills/10-developing-with-nix-shell.md b/pills/10-developing-with-nix-shell.md
index 07f9e4a..e71544a 100644
--- a/pills/10-developing-with-nix-shell.md
+++ b/pills/10-developing-with-nix-shell.md
@@ -37,9 +37,9 @@ The derivation didn't install, but it did build. Note the following:
 
 - We sourced `builder.sh` and it ran all of the build steps, including setting up the `PATH` for us.
 
-- The working directory is no longer a temp directory created by `nix-build`, but is instead the directory in which we entered the shell. Therefore, `hello-2.10` has been unpacked in the current directory.
+- The working directory is no longer a temp directory created by `nix-build`, but is instead the directory in which we entered the shell. Therefore, `hello-2.12.1` has been unpacked in the current directory.
 
-We are able to `cd` into `hello-2.10` and type `make`, because `make` is now available.
+We are able to `cd` into `hello-2.12.1` and type `make`, because `make` is now available.
 
 The take-away is that `nix-shell` drops us in a shell with the same (or very similar) environment used to run the builder.