diff --git a/include/stdlib.h b/include/stdlib.h
index 6dadb4cfd..8797e3b9c 100755
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -76,6 +76,7 @@ _PROTOTYPE( int getloadavg, (double *, int)				);
 
 #ifdef _MINIX
 _PROTOTYPE( int putenv, (const char *_name)				);
+_PROTOTYPE( int setenv, (const char *name, const char *val, const int f));
 
 /* According to POSIX, getopt should be in unistd.h. What do we do with
  * this?