diff --git a/tests/gc.sh b/tests/gc.sh
index 95669e25c..9d92ad758 100644
--- a/tests/gc.sh
+++ b/tests/gc.sh
@@ -56,25 +56,34 @@ testCollectGarbageD () {
     clearProfiles
     # Run two `nix-env` commands, should create two generations of
     # the profile
-    nix-env -f ./user-envs.nix -i foo-1.0
-    nix-env -f ./user-envs.nix -i foo-2.0pre1
-    [[ $(nix-env --list-generations | wc -l) -eq 2 ]]
+    nix-env -f ./user-envs.nix -i foo-1.0 "$@"
+    nix-env -f ./user-envs.nix -i foo-2.0pre1 "$@"
+    [[ $(nix-env --list-generations "$@" | wc -l) -eq 2 ]]
 
     # Clear the profile history. There should be only one generation
     # left
     nix-collect-garbage -d
-    [[ $(nix-env --list-generations | wc -l) -eq 1 ]]
+    [[ $(nix-env --list-generations "$@" | wc -l) -eq 1 ]]
 }
+
 # `nix-env` doesn't work with CA derivations, so let's ignore that bit if we're
 # using them
 if [[ -z "${NIX_TESTS_CA_BY_DEFAULT:-}" ]]; then
     testCollectGarbageD
 
+    # Run the same test, but forcing the profiles an arbitrary location.
+    rm ~/.nix-profile
+    ln -s $TEST_ROOT/blah ~/.nix-profile
+    testCollectGarbageD
+
     # Run the same test, but forcing the profiles at their legacy location under
     # /nix/var/nix.
     #
+    # Note that we *don't* use the default profile; `nix-collect-garbage` will
+    # need to check the legacy conditional unconditionally not just follow
+    # `~/.nix-profile` to pass this test.
+    #
     # Regression test for #8294
     rm ~/.nix-profile
-    ln -s $NIX_STATE_DIR/profiles/per-user/me ~/.nix-profile
-    testCollectGarbageD
+    testCollectGarbageD --profile "$NIX_STATE_DIR/profiles/per-user/me"
 fi