diff --git a/cache.h b/cache.h
index c9efe88e9e..521262f8b4 100644
--- a/cache.h
+++ b/cache.h
@@ -434,6 +434,7 @@ extern int set_git_dir_init(const char *git_dir, const char *real_git_dir, int);
 extern int init_db(const char *template_dir, unsigned int flags);
 
 extern void sanitize_stdfds(void);
+extern int daemonize(void);
 
 #define alloc_nr(x) (((x)+16)*3/2)
 
diff --git a/daemon.c b/daemon.c
index 503e03906c..eba1255684 100644
--- a/daemon.c
+++ b/daemon.c
@@ -1056,11 +1056,6 @@ static void drop_privileges(struct credentials *cred)
 	/* nothing */
 }
 
-static void daemonize(void)
-{
-	die("--detach not supported on this platform");
-}
-
 static struct credentials *prepare_credentials(const char *user_name,
     const char *group_name)
 {
@@ -1102,24 +1097,6 @@ static struct credentials *prepare_credentials(const char *user_name,
 
 	return &c;
 }
-
-static void daemonize(void)
-{
-	switch (fork()) {
-		case 0:
-			break;
-		case -1:
-			die_errno("fork failed");
-		default:
-			exit(0);
-	}
-	if (setsid() == -1)
-		die_errno("setsid failed");
-	close(0);
-	close(1);
-	close(2);
-	sanitize_stdfds();
-}
 #endif
 
 static void store_pid(const char *path)
@@ -1333,9 +1310,10 @@ int main(int argc, char **argv)
 	if (inetd_mode || serve_mode)
 		return execute();
 
-	if (detach)
-		daemonize();
-	else
+	if (detach) {
+		if (daemonize())
+			die("--detach not supported on this platform");
+	} else
 		sanitize_stdfds();
 
 	if (pid_file)
diff --git a/setup.c b/setup.c
index 6c3f85ff7a..713043ad50 100644
--- a/setup.c
+++ b/setup.c
@@ -787,3 +787,27 @@ void sanitize_stdfds(void)
 	if (fd > 2)
 		close(fd);
 }
+
+int daemonize(void)
+{
+#ifdef NO_POSIX_GOODIES
+	errno = ENOSYS;
+	return -1;
+#else
+	switch (fork()) {
+		case 0:
+			break;
+		case -1:
+			die_errno("fork failed");
+		default:
+			exit(0);
+	}
+	if (setsid() == -1)
+		die_errno("setsid failed");
+	close(0);
+	close(1);
+	close(2);
+	sanitize_stdfds();
+	return 0;
+#endif
+}