diff --git a/lib-src/env.c b/lib-src/env.c
index 35532e0360d..2ae81a630b8 100644
--- a/lib-src/env.c
+++ b/lib-src/env.c
@@ -96,6 +96,9 @@ void setenv ();
 void fatal ();
 char *myindex ();
 
+extern char *strerror ();
+
+
 main (argc, argv, envp)
      register int argc;
      register char **argv;