diff --git a/src/auto/configure b/src/auto/configure
index 13eaea6..d135948 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -12350,10 +12350,18 @@
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
+// These should be in stdlib.h, but it depends on _XOPEN_SOURCE.
+char *ptsname(int);
+int unlockpt(int);
+int grantpt(int);
+
 int
 main ()
 {
-ptsname(0);grantpt(0);unlockpt(0);
+
+		ptsname(0);
+		grantpt(0);
+		unlockpt(0);
   ;
   return 0;
 }