diff --git a/include/ac/alloca.h b/include/ac/alloca.h
index 69e823d841..e8bb452fe2 100644
--- a/include/ac/alloca.h
+++ b/include/ac/alloca.h
@@ -23,7 +23,7 @@
 #pragma alloca
 #  else
 #   ifndef alloca /* predefined by HP cc +Olibcalls */
-char *alloca ();
+extern char *alloca ();
 #   endif
 #  endif
 # endif
diff --git a/include/ac/setproctitle.h b/include/ac/setproctitle.h
index 2866d211f5..f97074e7c2 100644
--- a/include/ac/setproctitle.h
+++ b/include/ac/setproctitle.h
@@ -18,7 +18,7 @@
 #	include <libutil.h>
 #else
 	/* use lutil version */
-	void setproctitle LDAP_P((const char *fmt, ...));
+	extern void setproctitle LDAP_P((const char *fmt, ...));
 	extern int Argc;
 	extern char **Argv;
 #endif