diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 1f2891378..403178a5d 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -354,7 +354,7 @@ struct Common : InstallableCommand, MixProfile
         for (auto & i : {"TMP", "TMPDIR", "TEMP", "TEMPDIR"})
             out << fmt("export %s=\"$NIX_BUILD_TOP\"\n", i);
 
-        out << "eval \"$shellHook\"\n";
+        out << "eval \"${shellHook:-}\"\n";
 
         auto script = out.str();
 
diff --git a/tests/functional/nix-shell.sh b/tests/functional/nix-shell.sh
index 13403fadb..04c83138e 100644
--- a/tests/functional/nix-shell.sh
+++ b/tests/functional/nix-shell.sh
@@ -118,10 +118,10 @@ diff $TEST_ROOT/dev-env{,2}.json
 # Ensure `nix print-dev-env --json` contains variable assignments.
 [[ $(jq -r .variables.arr1.value[2] $TEST_ROOT/dev-env.json) = '3 4' ]]
 
-# Run tests involving `source <(nix print-dev-inv)` in subshells to avoid modifying the current
+# Run tests involving `source <(nix print-dev-env)` in subshells to avoid modifying the current
 # environment.
 
-set +u # FIXME: Make print-dev-env `set -u` compliant (issue #7951)
+set -u
 
 # Ensure `source <(nix print-dev-env)` modifies the environment.
 (