diff --git a/src/libfetchers/git-utils.cc b/src/libfetchers/git-utils.cc
index b54416b10..6a75daf61 100644
--- a/src/libfetchers/git-utils.cc
+++ b/src/libfetchers/git-utils.cc
@@ -206,7 +206,8 @@ static git_packbuilder_progress PACKBUILDER_PROGRESS_CHECK_INTERRUPT = &packBuil
 
 } // extern "C"
 
-static void initRepoAtomically(std::filesystem::path &path, bool bare) {
+static void initRepoAtomically(std::filesystem::path &path, bool bare)
+{
     if (pathExists(path.string())) return;
 
     Path tmpDir = createTempDir(os_string_to_string(PathViewNG { std::filesystem::path(path).parent_path() }));
@@ -544,13 +545,10 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
         //       then use code that was removed in this commit (see blame)
 
         auto dir = this->path;
-        Strings gitArgs;
-        if (shallow) {
-            gitArgs = { "-C", dir.string(), "fetch", "--quiet", "--force", "--depth", "1", "--", url, refspec };
-        }
-        else {
-            gitArgs = { "-C", dir.string(), "fetch", "--quiet", "--force", "--", url, refspec };
-        }
+        Strings gitArgs{"-C", dir.string(), "--git-dir", ".", "fetch", "--quiet", "--force"};
+        if (shallow)
+            append(gitArgs, {"--depth", "1"});
+        append(gitArgs, {std::string("--"), url, refspec});
 
         runProgram(RunOptions {
             .program = "git",
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 4d5683e2b..0d55cf93b 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -274,6 +274,17 @@ std::optional<typename T::value_type> pop(T & c)
 }
 
 
+/**
+ * Append items to a container. TODO: remove this once we can use
+ * C++23's `append_range()`.
+ */
+template<class C, typename T>
+void append(C & c, std::initializer_list<T> l)
+{
+    c.insert(c.end(), l.begin(), l.end());
+}
+
+
 template<typename T>
 class Callback;
 
diff --git a/tests/functional/common/vars.sh b/tests/functional/common/vars.sh
index 4b88e8526..ed4b47727 100644
--- a/tests/functional/common/vars.sh
+++ b/tests/functional/common/vars.sh
@@ -60,6 +60,7 @@ unset XDG_DATA_HOME
 unset XDG_CONFIG_HOME
 unset XDG_CONFIG_DIRS
 unset XDG_CACHE_HOME
+unset GIT_DIR
 
 export IMPURE_VAR1=foo
 export IMPURE_VAR2=bar