diff --git a/trace.c b/trace.c
index 02279b82c4..35d388dce4 100644
--- a/trace.c
+++ b/trace.c
@@ -154,6 +154,7 @@ static const char *quote_crnl(const char *path)
 /* FIXME: move prefix to startup_info struct and get rid of this arg */
 void trace_repo_setup(const char *prefix)
 {
+	const char *git_work_tree;
 	char cwd[PATH_MAX];
 	char *trace = getenv("GIT_TRACE");
 
@@ -164,8 +165,14 @@ void trace_repo_setup(const char *prefix)
 	if (!getcwd(cwd, PATH_MAX))
 		die("Unable to get current working directory");
 
+	if (!(git_work_tree = get_git_work_tree()))
+		git_work_tree = "(null)";
+
+	if (!prefix)
+		prefix = "(null)";
+
 	trace_printf("setup: git_dir: %s\n", quote_crnl(get_git_dir()));
-	trace_printf("setup: worktree: %s\n", quote_crnl(get_git_work_tree()));
+	trace_printf("setup: worktree: %s\n", quote_crnl(git_work_tree));
 	trace_printf("setup: cwd: %s\n", quote_crnl(cwd));
 	trace_printf("setup: prefix: %s\n", quote_crnl(prefix));
 }