diff --git a/garage.nix b/garage.nix
index b58738d..478443d 100644
--- a/garage.nix
+++ b/garage.nix
@@ -175,7 +175,7 @@ in {
 
         # Give garage time to start up by waiting until somethings speaks HTTP
         # behind localhost:3900.
-        until curl -sio /dev/null http://localhost:3900/; do sleep 1; done
+        until ${pkgs.curl}/bin/curl -sio /dev/null http://localhost:3900/; do sleep 1; done
 
         # XXX: this is very sensitive to being a single instance
         # (doing the bare minimum to get garage up and running)
diff --git a/tests/pixelfed-garage.nix b/tests/pixelfed-garage.nix
index e084cb0..a08a312 100644
--- a/tests/pixelfed-garage.nix
+++ b/tests/pixelfed-garage.nix
@@ -29,15 +29,16 @@ let
     print("Open login page...", file=sys.stderr)
     driver.get("http://pixelfed.localhost/login")
     print("Enter email...", file=sys.stderr)
-    driver.find_element(By.ID, "email").send_keys(${email})
+    driver.find_element(By.ID, "email").send_keys("${email}")
     print("Enter password...", file=sys.stderr)
-    driver.find_element(By.ID, "password").send_keys(${password})
+    driver.find_element(By.ID, "password").send_keys("${password}")
     # FIXME: This is disgusting. Find instead the input type submit in the form
     # with action ending in "/login".
     print("Click “Login” button...", file=sys.stderr)
     driver.find_element(By.XPATH, "//button[normalize-space()='Login']").click()
   '';
 
+  ## NOTE: `path` must be a valid python string, either a variable or _quoted_.
   seleniumTakeScreenshot = path: ''
     print("Take screenshot...", file=sys.stderr)
     if not driver.save_screenshot(${path}):
@@ -172,7 +173,7 @@ pkgs.nixosTest {
       server.wait_for_unit("phpfpm-pixelfed.service")
 
     with subtest("Account creation"):
-      server.succeed(f"pixelfed-manage user:create --name=test --username=test --email=${email} --password=${password} --confirm_email=1")
+      server.succeed("pixelfed-manage user:create --name=test --username=test --email=${email} --password=${password} --confirm_email=1")
 
     # NOTE: This could in theory give a false positive if pixelfed changes it's
     # colorscheme to include pure green. (see same problem in pixelfed-garage.nix).
@@ -180,7 +181,7 @@ pkgs.nixosTest {
     # there, then post a green image and check that the green pixel IS there.
 
     with subtest("Image displays"):
-      server.succeed(f"su - selenium -c 'selenium-script-post-picture ${email} ${password}'")
+      server.succeed("su - selenium -c 'selenium-script-post-picture ${email} ${password}'")
       server.copy_from_vm("/home/selenium/screenshot.png", "")
       displayed_colors = server.succeed("magick /home/selenium/screenshot.png -define histogram:unique-colors=true -format %c histogram:info:")
       # check that the green image displayed somewhere
@@ -193,7 +194,7 @@ pkgs.nixosTest {
       server.succeed("mc ls garage/pixelfed")
 
     with subtest("access image in garage"):
-      image = server.succeed("mc find garage --regex '\.png' --ignore '*_thumb.png'")
+      image = server.succeed("mc find garage --regex '\\.png' --ignore '*_thumb.png'")
       image = image.rstrip()
       if image == "":
         raise Exception("image posted to mastodon did not get stored in garage")
@@ -204,7 +205,7 @@ pkgs.nixosTest {
         raise Exception("image stored in garage did not match image uploaded")
 
     with subtest("Check that image comes from garage"):
-      src = server.succeed(f"su - selenium -c 'selenium-script-get-src ${email} ${password}'")
+      src = server.succeed("su - selenium -c 'selenium-script-get-src ${email} ${password}'")
       if not src.startswith("http://pixelfed.web.garage.localhost:3902/"):
         raise Exception("image does not come from garage")
   '';