diff --git a/elf/firstobj.c b/elf/firstobj.c
index 1e7cb50fd2..2e6033eab6 100644
--- a/elf/firstobj.c
+++ b/elf/firstobj.c
@@ -1,5 +1,7 @@
 #include <errno.h>
 
+extern int foo (void);
+
 int
 foo (void)
 {