diff --git a/t/helper/test-cmp.c b/t/helper/test-cmp.c
index 98dd0791520fe0..1c646a54bf609b 100644
--- a/t/helper/test-cmp.c
+++ b/t/helper/test-cmp.c
@@ -5,6 +5,12 @@
 #include "parse-options.h"
 #include "run-command.h"
 
+#ifdef WIN32
+#define NO_SUCH_DIR "\\\\.\\GLOBALROOT\\invalid"
+#else
+#define NO_SUCH_DIR "/dev/null"
+#endif
+
 static int run_diff(const char *path1, const char *path2)
 {
 	const char *argv[] = {
@@ -12,8 +18,8 @@ static int run_diff(const char *path1, const char *path2)
 	};
 	const char *env[] = {
 		"GIT_PAGER=cat",
-		"GIT_DIR=/dev/null",
-		"HOME=/dev/null",
+		"GIT_DIR=" NO_SUCH_DIR,
+		"HOME=" NO_SUCH_DIR,
 		NULL
 	};
 
diff --git a/t/t0001-init.sh b/t/t0001-init.sh
index 7c48ed2aba2843..7f19368fc10b43 100755
--- a/t/t0001-init.sh
+++ b/t/t0001-init.sh
@@ -307,10 +307,20 @@ test_expect_success 'init prefers command line to GIT_DIR' '
 	test_path_is_missing otherdir/refs
 '
 
+downcase_on_case_insensitive_fs () {
+	test false = "$(git config --get core.filemode)" || return 0
+	for f
+	do
+		tr A-Z a-z <"$f" >"$f".downcased &&
+		mv -f "$f".downcased "$f" || return 1
+	done
+}
+
 test_expect_success 'init with separate gitdir' '
 	rm -rf newdir &&
 	git init --separate-git-dir realgitdir newdir &&
 	echo "gitdir: $(pwd)/realgitdir" >expected &&
+	downcase_on_case_insensitive_fs expected newdir/.git &&
 	test_cmp expected newdir/.git &&
 	test_path_is_dir realgitdir/refs
 '
@@ -365,6 +375,7 @@ test_expect_success 're-init to update git link' '
 	git init --separate-git-dir ../surrealgitdir
 	) &&
 	echo "gitdir: $(pwd)/surrealgitdir" >expected &&
+	downcase_on_case_insensitive_fs expected newdir/.git &&
 	test_cmp expected newdir/.git &&
 	test_path_is_dir surrealgitdir/refs &&
 	test_path_is_missing realgitdir/refs
@@ -378,6 +389,7 @@ test_expect_success 're-init to move gitdir' '
 	git init --separate-git-dir ../realgitdir
 	) &&
 	echo "gitdir: $(pwd)/realgitdir" >expected &&
+	downcase_on_case_insensitive_fs expected newdir/.git &&
 	test_cmp expected newdir/.git &&
 	test_path_is_dir realgitdir/refs
 '