diff --git a/tests/modules/programs/firefox/profile-settings.nix b/tests/modules/programs/firefox/profile-settings.nix
index b90fd919..b139545e 100644
--- a/tests/modules/programs/firefox/profile-settings.nix
+++ b/tests/modules/programs/firefox/profile-settings.nix
@@ -21,7 +21,7 @@ with lib;
           preferLocalBuild = true;
           allowSubstitutes = false;
         } ''
-          mkdir -p "$out/bin"
+          mkdir -p "$out"/{bin,lib}
           touch "$out/bin/firefox"
           chmod 755 "$out/bin/firefox"
         '';
diff --git a/tests/modules/programs/firefox/state-version-19_09.nix b/tests/modules/programs/firefox/state-version-19_09.nix
index 27dc867a..9106127f 100644
--- a/tests/modules/programs/firefox/state-version-19_09.nix
+++ b/tests/modules/programs/firefox/state-version-19_09.nix
@@ -15,7 +15,7 @@ with lib;
           preferLocalBuild = true;
           allowSubstitutes = false;
         } ''
-          mkdir -p "$out/bin"
+          mkdir -p "$out"/{bin,lib}
           touch "$out/bin/firefox"
           chmod 755 "$out/bin/firefox"
         '';