diff --git a/git.c b/git.c
index 96b0a2837d..6171fd6769 100644
--- a/git.c
+++ b/git.c
@@ -430,7 +430,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 		use_pager = 1;
 	if (run_setup && startup_info->have_repository)
 		/* get_git_dir() may set up repo, avoid that */
-		trace_repo_setup(prefix);
+		trace_repo_setup();
 	commit_pager_choice();
 
 	if (!help && p->option & NEED_WORK_TREE)
diff --git a/trace.c b/trace.c
index 794a087c21..efa4e2d8e0 100644
--- a/trace.c
+++ b/trace.c
@@ -291,10 +291,9 @@ static const char *quote_crnl(const char *path)
 	return new_path.buf;
 }
 
-/* FIXME: move prefix to startup_info struct and get rid of this arg */
-void trace_repo_setup(const char *prefix)
+void trace_repo_setup(void)
 {
-	const char *git_work_tree;
+	const char *git_work_tree, *prefix = startup_info->prefix;
 	char *cwd;
 
 	if (!trace_want(&trace_setup_key))
@@ -305,7 +304,7 @@ void trace_repo_setup(const char *prefix)
 	if (!(git_work_tree = get_git_work_tree()))
 		git_work_tree = "(null)";
 
-	if (!prefix)
+	if (!startup_info->prefix)
 		prefix = "(null)";
 
 	trace_printf_key(&trace_setup_key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
diff --git a/trace.h b/trace.h
index 4e771f86ac..b6e35b9470 100644
--- a/trace.h
+++ b/trace.h
@@ -93,7 +93,7 @@ extern struct trace_key trace_default_key;
 extern struct trace_key trace_perf_key;
 extern struct trace_key trace_setup_key;
 
-void trace_repo_setup(const char *prefix);
+void trace_repo_setup(void);
 
 /**
  * Checks whether the trace key is enabled. Used to prevent expensive