diff --git a/ext/I18N-Langinfo/Langinfo.xs b/ext/I18N-Langinfo/Langinfo.xs
index 8b1fd5a4ef0c..582b7fa634c6 100644
--- a/ext/I18N-Langinfo/Langinfo.xs
+++ b/ext/I18N-Langinfo/Langinfo.xs
@@ -23,7 +23,12 @@ langinfo(code)
   PROTOTYPE: _
   CODE:
 #ifdef HAS_NL_LANGINFO
-	RETVAL = newSVpv(nl_langinfo(code), 0);
+	if (code < 0) {
+	    SETERRNO(EINVAL, LIB_INVARG);
+	    RETVAL = &PL_sv_undef;
+	} else {
+            RETVAL = newSVpv(nl_langinfo(code), 0);
+        }
 #else
 	croak("nl_langinfo() not implemented on this architecture");
 #endif