diff --git a/t/t1510-repo-setup.sh b/t/t1510-repo-setup.sh
index 25f7c015e..2596f7ff7 100755
--- a/t/t1510-repo-setup.sh
+++ b/t/t1510-repo-setup.sh
@@ -2225,4 +2225,139 @@ EOF
 	test_repo 15/sub/sub "$TRASH_DIRECTORY/15/.git" "$TRASH_DIRECTORY"
 '
 
+#
+# case #16.1
+#
+############################################################
+#
+# Input:
+#
+#  - GIT_WORK_TREE is not set
+#  - GIT_DIR is not set
+#  - core.worktree is not set
+#  - .git is a directory
+#  - cwd is inside .git
+#
+# Output:
+#
+#  - no worktree
+#  - cwd is unchanged
+#  - prefix is NULL
+#  - git_dir is set
+#  - cwd can't be outside worktree
+
+test_expect_success '#16.1: setup' '
+	unset GIT_DIR GIT_WORK_TREE &&
+	mkdir 16 16/sub &&
+	cd 16 &&
+	git init &&
+	mkdir .git/wt .git/wt/sub &&
+	cd ..
+'
+
+test_expect_success '#16.1: at .git' '
+	cat >16/.git/expected <<EOF &&
+setup: git_dir: .
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/.git
+setup: prefix: (null)
+EOF
+	test_repo 16/.git
+'
+
+test_expect_success '#16.1: in .git/wt' '
+	cat >16/.git/wt/expected <<EOF &&
+setup: git_dir: $TRASH_DIRECTORY/16/.git
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/.git/wt
+setup: prefix: (null)
+EOF
+	test_repo 16/.git/wt
+'
+
+test_expect_success '#16.1: in .git/wt/sub' '
+	cat >16/.git/wt/sub/expected <<EOF &&
+setup: git_dir: $TRASH_DIRECTORY/16/.git
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/.git/wt/sub
+setup: prefix: (null)
+EOF
+	test_repo 16/.git/wt/sub
+'
+
+#
+# case #16.2
+#
+############################################################
+#
+# Input:
+#
+#  - GIT_WORK_TREE is not set
+#  - GIT_DIR is not set
+#  - core.worktree is not set
+#  - .git is a directory
+#  - core.bare is set
+#
+# Output:
+#
+#  - no worktree
+#  - cwd is unchanged
+#  - prefix is NULL
+#  - git_dir is set
+#  - cwd can't be outside worktree
+
+test_expect_success '#16.2: setup' '
+	git config --file="$TRASH_DIRECTORY/16/.git/config" core.bare true
+'
+
+test_expect_success '#16.2: at .git' '
+	cat >16/.git/expected <<EOF &&
+setup: git_dir: .
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/.git
+setup: prefix: (null)
+EOF
+	test_repo 16/.git
+'
+
+test_expect_success '#16.2: in .git/wt' '
+	cat >16/.git/wt/expected <<EOF &&
+setup: git_dir: $TRASH_DIRECTORY/16/.git
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/.git/wt
+setup: prefix: (null)
+EOF
+	test_repo 16/.git/wt
+'
+
+test_expect_success '#16.2: in .git/wt/sub' '
+	cat >16/.git/wt/sub/expected <<EOF &&
+setup: git_dir: $TRASH_DIRECTORY/16/.git
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/.git/wt/sub
+setup: prefix: (null)
+EOF
+	test_repo 16/.git/wt/sub
+'
+
+test_expect_success '#16.2: at root' '
+	cat >16/expected <<EOF &&
+setup: git_dir: .git
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16
+setup: prefix: (null)
+EOF
+	test_repo 16
+'
+
+test_expect_failure '#16.2: in subdir' '
+	cat >16/sub/expected <<EOF &&
+setup: git_dir: $TRASH_DIRECTORY/16/.git
+setup: worktree: (null)
+setup: cwd: $TRASH_DIRECTORY/16/sub
+setup: prefix: (null)
+EOF
+	test_repo 16/sub
+'
+
 test_done