diff --git a/setup.c b/setup.c
index 029371e..4272ec0 100644
--- a/setup.c
+++ b/setup.c
@@ -18,9 +18,12 @@
 	if (normalize_path_copy(sanitized, sanitized))
 		goto error_out;
 	if (is_absolute_path(orig)) {
+		size_t len, total;
 		const char *work_tree = get_git_work_tree();
-		size_t len = strlen(work_tree);
-		size_t total = strlen(sanitized) + 1;
+		if (!work_tree)
+			goto error_out;
+		len = strlen(work_tree);
+		total = strlen(sanitized) + 1;
 		if (strncmp(sanitized, work_tree, len) ||
 		    (sanitized[len] != '\0' && sanitized[len] != '/')) {
 		error_out:
diff --git a/t/t1501-worktree.sh b/t/t1501-worktree.sh
index f6a6f83..74e6443 100755
--- a/t/t1501-worktree.sh
+++ b/t/t1501-worktree.sh
@@ -174,4 +174,19 @@
 	GIT_DIR=../.. GIT_WORK_TREE=.. git grep -l changed | grep dir/tracked)
 '
 
+test_expect_success 'git commit' '
+	(
+		cd repo.git &&
+		GIT_DIR=. GIT_WORK_TREE=work git commit -a -m done
+	)
+'
+
+test_expect_success 'absolute pathspec should fail gracefully' '
+	(
+		cd repo.git || exit 1
+		git config --unset core.worktree
+		test_must_fail git log HEAD -- /home
+	)
+'
+
 test_done