diff --git a/apps/prime.c b/apps/prime.c
index 1753b3ebc..36bbe0841 100644
--- a/apps/prime.c
+++ b/apps/prime.c
@@ -56,6 +56,8 @@
 #undef PROG
 #define PROG prime_main
 
+int MAIN(int, char **);
+
 int MAIN(int argc, char **argv)
     {
     int hex=0;